Ah yes, GTA4 and GTA5. I have something to say about it too.
I think it's unfair to look at GTA IV through the lens of the 3D era games, and not look at it through the pure "complete mayhem power fantasy" prism. Because sure, under that aspect IV sucks. You have a weak selection of weaponry and the map is probably more restricted than III's. However when it comes to the story writing it's the best GTA game in the series. All the characters are fantastic, and the fact that you don't end up with a super awesome Hollywood happy ending was definitely fresh. Unless you want to be cynical and say it was too negative.
By the end of III you were the king of Liberty City and you haven't lost anything of value. By the end of VC you were the king of Vice City and you also haven't lost anything of value. Same with SA, the only tragic thing that happened to CJ was the death of his mom, but that happened even before the first cutscene of the game. Every protagonist of the trilogy was an American without a major anguish (besides CJ losing Moms), and their entire story was a story of major success and ruling over the entire game's map. And every single one of them was an unhinged psychopath.
GTA IV finally broke that by making a protagonist that is a Serbian war veteran that illegally immigrated into the US to take revenge on a man who betrayed him during the war. We finally have a protagonist that looks at the US culture though an eye of a cynical European. We also have a protagonist that's actually tragic, before we start the game and after we finish it. And also, we finally have a protagonist that's not an unhinged psychopath, but rather a man that has experienced a lot of pain in his life and sees killing as simply the only job he is capable of doing, and he actually tries to fit into society and act like a decent person despite being a career criminal as that's the only life he knows. And by the end of his story he either loses the only family member he has in this completely alien city and gets dumped by the love of his life, or he loses the love of his life. And we get plenty of moments where we can decide on who gets to live and who gets to die, making the game more interesting. Now of course I know that people in this thread will say that it's just pretentious contrarianism, yet they don't see an issue with the trilogy following the same scheme. But honestly I don't care, the same type of people probably hates everything that's popular just because it's popular.
As for the limitations in what you could do in IV compared to SA, it's worth noting something important. San Andreas was the peak of R* pushing the RenderWare engine on the PS2 to it's limits. And by the year of release of San Andreas, RenderWare was bought out by EA, so R* was forced to make their own in-house solution. This led to the creation of RAGE, and GTA IV was the first GTA game to be made on this engine. And because their new engine was so demanding, and this was their first GTA game of this scale on the new engine, it has led to features from SA being cut or diluted for IV. Therefore you no longer have a clothing system that's as extensive as SA's, you no longer have the RPG elements such as fat and muscle, you don't have vehicle customization and so on and so forth. Basically the reason people dislike IV so much compared to SA was simply because R* wasn't able to port every single piece of mechanic they've made for SA into their new engine that was way more complex and way more resource demanding. The amount of shit they've added in V shows that it was possible, but only after they've got a hang of it.
And as for V, it is definitely inferior to IV in every way, no doubt. It's probably a good allegory of the current gaming industry. It boasted itself as being bigger and better than IV, but the end product seems artificially pumped up for the sake of being bigger. Sure, you have a massive map, but the said map is mostly empty rural areas that have nothing to do. Sure you have all those crazy cars, but they handle even worse than SA cars. They wanted to make them more "arcadey" than the ones in IV because people were complaining that the cars in IV handled like shit, but in the end they've made them handle even less realistically than they did in SA. Similarly a lot of small details that were very impressive in IV got diluted. Euphoria ragdolls got dumbed down, vehicle damage got dumbed down, a lot of it was significantly worsened, and V feels more technologically backwards than IV because of that.
And as for V's story, it is in fact the worse in the series. It's possible that originally there was only supposed to be one protagonist, Michael, but then they went for the "3 simultaneous protagonists" gimmick, but even then, the writing of the story and characters is insanely idiotic and even more Hollywood-y than even San Andreas. All three protagonists do some crazy heists, dealings with the feds and whatnot, explosions, action, everything at once, and by the end you have three choices, with the third one being the most happy ending super rainbow Hollywood ending imaginable where you kill all the feds and influential people that were a problem for you and you never get chased for doing so. And the other two endings is you meaninglessly killing off either Michael or Trevor because the fed told you to. Basically no one ever picked those endings and they were only there to be some allusion to how IV only had bad endings but now we have a third good ending so it's all good.
And speaking of that ending, R* has a fucking fetish of retconning every potential storyline choice of V into being the true canon ending. For example those three endings, Online made it canon that both Michael and Trevor are alive, making Ending C the canon choice. They went so far with this that they've made it canon that Michael didn't kill his asshole psychiatrist. At this point everyone should consider everything from Online as a retarded millennial fanfiction that has nothing to do with what happened in the singleplayer campaign.
As a final remark, GTA V was the sign of R* running out of steam. They had no idea what to do with that game, and their final product was inferior to both IV and SA. And after the release of V, T2 has decided that R* should focus on the Online part as it brings in the most cash, and in that time Leslie Benzies, Dan Houser and Lazlow Jones left the company, which strongly implies that R* as a brand is over, and nothing that they may release in the future will be as good as what released before. Not that having that trio still in the company would help much, but with them out of the picture it will definitely make things worse.
ffs I wrote an entire fucking essay over this