@Alter Ego
Anyone who argues that the Imperium are bad guys is hooked on copium, including GW whenever they cry satire in damage-controlling public statements. The truth is that despite the "grimdark" setting, 40k is chocked full of heroic narratives of good versus evil with the human-centric Imperium in the starring role for consumers to find commonality with. It's worth noting that in both major eras (30k and 40k), the Imperium is on the defense, and its militarism is completely justified in light of the numerous non-negotiable, genocidal forces it's set against. This defensive war is further emphasized in recent years as the current storyline of the Indomitus Crusade is not about the Guilliman-led Imperium conquering new territory, but rather recovering losses from the Great Rift. On the micro level, individual stories constantly provide virtuous protagonists who glorify the Emperor and fight on behalf of the Imperium against existential threats, sometimes even though they've been personally wronged by the Imperium in some fashion.
It's basically a thing I've seen with British sci-fi and comics. 2000 AD wants you to see Judge Dredd as a fascist oppressor, Alan Moore wants Rorschach to be a warning against costumed superheroes, and Games Workshop's left-wing authors wanted you to see the Space Marines the same way one would look at a member of the Taliban, or a Nazi SS officer.
But people don't. Instead, they love the Space Marines. They love Judge Dredd. They love Rorschach. Why is that?
Because people love characters who fight for what they believe, even when the authors don't.
The writers of things like Judge Dredd, Warhammer 40K, and Watchmen approach things from a post-modern ''nothing is right'' point of view, where there is no objective right or wrong, aside from their point of view that the only true evils are the far-right militarists, law enforcement, and religious nutjobs. Britain, which had long been torn between tradition and progressivism, was a breeding ground for such subversive thoughts, especially since many among the British Left really despised how politics were like during the 80s. The Soviets fell, the religious right regained a lot of authority that they lost in the past two centuries, the Anglosphere was ruled by conservative politicians, etc.. Stories like 40K were originally created by anti-religious, anti-right wing nerds who were pissed off that Margaret Thatcher was their prime minister while Reagan was president in the USA. So they expressed their anger through fiction, creating bombastic, brutal, illogical morons who represent everything that they hate. But instead of being hated, these characters wound up being loved.
In 40K, the supposed ''real evil'' is the Imperium and its dogmatic ways; the original intent of the story when it was first written is that the Space Marines and the Imperium would be halfway to solving all their problems if they all held hands together, sang koombayah, and abandoned all that religious and xenophobic stuff for ''rational thought'' and the enlightenment-era's anti-religious notions of reason. The whole story was written as a big fat ''fuck you'' to the Middle Ages' Age of Faith, showing how even a high-tech society can crumble into superstition and idiocy if it adopts certain religious beliefs.
If the original writers of 40K's story could write an ending to it, they'd have the Emperor come back from the dead, only for him to tear down the Imperial Cult, tear down anything religious or fanatical about the Imperium, go full Voltaire and turn the Imperium into an enlightened despot state, and they'd solve every problem in the galaxy, from Chaos, to the Tyranids, to the Orks and Dark Eldar, through a judicious application of science, reason, and atheist logic, and the Emperor passes the torch on to the next generation of secular leaders who rule with reason and kindness.
That, or the Emperor remains dead, the Imperium keeps going on as a state full of superstitious quacks, and they all get eaten by the Orks, Chaos, or Tyranids when their inability to tolerate other aliens and dismiss religion for ''reason'' leads to their demise.
But the story has changed to the point where, if the Imperium did abandon religion, they'd handicap themselves since praying to the Emperor grants them miracles, and all that human sacrifice, both on the battlefield and on the Golden Throne, keeps the Chaos gods and other enemies of man in check. Mostly because fans of the Space Marines and the Imperium got hired by GW to write stories, since they need to sell books to people who buy Space Marine minis, and to no-one's great surprise, they re-tooled the story to make a lot of what the Imperium does to be correct. Researching new tech is dangerous and can lead to corruption. Praying to the Emperor, instead of being the 40K equivalent of offering incense to a false idol, grants you miracles that can heal and protect you.
Thanks to all these changes, a lot of people who believe in nationalism, religion, and tradition became fans of 40K. If the Emperor suddenly came back and shat all over that stuff, they'd lose their new fanbase. Hence why GW plays both sides by paying lip service to the idea of 40K being a satire of religion and fascism, but not actually going through with it.
You also have to look at the modern culture and it's social angle, which I argue had a LOT of influence on how people see 40K today. Back in the 90s and early 2000s, when the West was still optimistic and Christian, few people would give a damn about a series like Warhammer 40K due to it being too dark; it'd be like Starcraft or Fallout where the story is dark and interesting, but the culture is optimistic and bright, and no one would really care about things like that. 40K was just be in the backburner while kids obsessed over things like Star Wars, Lord of the Rings, Dragon Ball Z, Naruto, the DC and Marvel movies, the Transformers series, other anime and video game franchises, and so on. When you mentioned the word ''Space Marine'', the average dork thinks about the armor-clad warriors from Starcraft, Halo, Gears of War, or the soldiers from films such as Aliens, Starship Troopers, or James Cameron's Avatar. They wouldn't think about the Space Marines of 40K.
But years of the Left having dominated the political discourse in the post-Bush years, combined with the Left's constant worship of subjective, subversive ideology that shits all over everything that many people know and love, from religion, to nationalism, to masculinity and family values, has made people sick to death of that shit, enough to the point where people turn to things like 40K as a substitute, especially with the Left controlling things like the MCU and Star Wars. People, especially from the right, are sick to death of liberals telling them that national identity isn't worth defending because they're imperialist dogs, that their beliefs are wrong, that their most cherished ideas and faiths are not part of the new, modern, secular world, that they're sexist pigs for looking at a chick with hot tits, or that they're monsters for not wanting to get in bed with a "woman" who happens to be a mutilated man. People are sick to death of such things.
Then these people see an Imperial Space Marine covered head to toe in religious imagery that hearkens to old Christendom, and he's gutting a Daemon Prince that looks like a Balrog of Morgoth for his Emperor, and they like it. The Space Marine is someone who stands for something; he stands for his king, his country, his people, and he's willing to give everything in defense of it all. He fights for a nation that believes in its god with full faith and trust, and they would rather die than see it be subverted by outsiders or daemon-worshipers, or destroyed by alien filth who see mankind as target practice at best or rape-slaves and dinner at worst.
These people see that and are inspired by it. Even if the marine is fighting for a lie, even if the guy is just holding back an inevitable doom, the courage and strength in such an image inspires hope for someone in the real world tired of being told that he's a monster for who he is or what he believes. This show of heroism despite inevitable odds isn't what the original authors of 40K wished to impart, but it is what many people get from these stories, even though the OG authors of 40K wouldn't approve.
Because at the end of the day, what did the original authors of 40K believe in when they made the Space Marines as the bad guys for their ''satirical'' work? That Margaret Thatcher sucks? That religion, tradition, and militarism are for fascist buffoons who just go full lock-step with the authorities? That the real answer to all our problems is to hold our hands, sing koombayah, go full secular Communist, and get rid of religion and tradition and go full-in on an atheistic view of science and social progress?
In the schools, that can sound interesting to some dupes. But in the real world? THAT SHIT IS BORING. People want to see things blow up! They want heroes fighting to their last breath against an evil that mortal minds cannot comprehend! They want last stands by brave men who are walking symbols of faith and strength, fighting against evil, degeneracy, corruption, and monsters that lurk from the darkness that come from the great unknown. And 40K gives them that in spades, whether or not it was intended.
This explains why a lot of the Trump-stans chose 40K as their fiction of choice for their memes, and why a lot of people tired of the Left chose 40K as a means of cultural protest against the safe, MCU-style culture of the modern Left-leaning media. I even remember some 40K fans tried to get SW fans to join them when the SW fans got pissed at the Last Jedi, with one fan trying to sell the premise of 40K to SW fans by saying that the series is so dark that ''the Catholic Space Nazis are the good guys''.
You have a similar situation with Watchmen creator Alan Moore, who created Rorshach as a parody of how brutal and violent superheroes can be, but people wound up liking him instead, since he stands for morals and is unwilling to compromise them, even in the face of Armageddon. Alan Moore was disgusted when people came out to see Rorschach as a hero, but any idiot who's spent a day outside of seeing the world from a Leftist lens would have seen the innate appeal of someone who stands for morality in a world that seems to spit on the very concept of decency. Hence why the Watchmen movie portrayed Rorschach as a badass instead of a loony; most fans of the comic love him and what he stands for, despite of, or sometimes, because of the lengths he'll go to uphold his vision of justice.
The same thing happened with Judge Dredd. How many fans of his see him as a bad guy, or an enforcer of a tyrannical regime? Compare that to the number of fans who see him as a badass who dispenses righteous justice against wretches and scum who deserve to be eradicated. Your average Judge Dredd fan sees Dredd and his fellow Judges as the good guys, and even both film adaptations of Dredd portray the Judges as somewhat good, with only a few bad apples in the bunch serving as bad guys now and then. But they were not originally meant to be good guys; the Judges took over the USA and enforce laws on the point of a gun, ripping apart any other government force that could've checked their power.
The people who originally wrote these works laugh at traditional values and make their flawed characters be based upon said values; they were basically Brits who were ass-mad that Thatcher and Reagan were both conservatives who ruled the Anglosphere in the 80s. But they failed to notice how those values are so universal that some people will inevitably be inspired by said flawed characters who stand for truths that people have believed for centuries; that your God and your nation is worth fighting for, and standing up for what's right, even in the face of overwhelming odds, is laudable and heroic.
This is what you'd call a classic case of ''death of the author''. As in, a work takes a life of its own and surpasses what its authors originally intended it to be.
All the more reason to not let trannies utterly obliterate this last gem.
Sad to say this, but GW doesn't care, and 40K is theirs to fuck with. Right now, they're entertaining Space Marine fanboys who veer center-right because they buy minis and books; if that changes and the trannies start flashing some serious cash at GW products, GW will change their tune in less than a day and let the Trannies rewrite the lore upside-down.
Remember what happened with the Primaris Marines. The Imperium from 3rd-7th Edition would've never accepted them. 40K lore is something GW can easily rewrite at will. They already butchered the lore to force you to buy new Space Marine models; they can butcher it some more if someone else is willing to flash enough cash their way.