Never underestimate human ingenuity
What you underestimate here: Putting in the gun sideways, cutting a hole to make the radio fit, rigging together a bunch of car engines to make it go... Those are solutions to problems the engineers had to get over, to make the tank transition from some vague design to a reality. And it very well represents the clash between a design and how to realize it. All of these mitigations of problems likely come with some sort of downside that the real tank has to deal with, while the one on paper didn't.
Let me put it like this:
Someone has an idea for a tank, he needs a "sales pitch" so the Army will greenlight it and he embelishes the design a bit, hoping to figure out how to make it once he gets down to building it:
So he'll assume it'll weigh 50 tons, with a low profile sloped turret and a super compact 100mm gun that can fire 10 rounds a minute and carry 60 rounds, front armor of a certain composition and shape (say wedge shape with 120mm armor), and an engine with 800hp at a weight of 1 ton that can propel the tank to 60km/h on streets and 35km/h on dirt.
If the project was shitcanned during the design-phase, you get a (50 Euro Premium) tank with all the amazing, albeit unrealistic, features someone hoped to put into the finished product before he was confronted with a shortage of supplies, being forced to use surplus parts from other projects or make do with whatever leftover stuff lying around from previous developements he could find.
Now, instead, Hitler likes this design a lot and goes "Make me 10.000 of those" and it is actually built:
So the engineers get down to business and figure out, that the gun they want to use does not exist and they need to go for some old 75mm PAK gun - and even that will be a tight fit in the turret, which ends up overweight due to some design flaw they overlooked. Worse still, they figure out they only got a 500hp engine that weighs 1.5tons as the intended engine is too expensive and the suspension is a nightmare to design, which also goes over the weight that they first assumed when designing the tank. In order to mitigate this to retain some of the mobility, they downgrade the armor and the tank still weighs more than planned.
You ultimately get a 55-60 ton tank that is not as well armored, has a gun that is smaller and can only fire 5 rounds per minute and only carry 40 rounds due to the cramped turret. It now only drives 40km/h on the road and easily bogs down in the dirt.
And this is what you get in WoT.
There's some french scout tank, that's flat as a flounder (literally impossible to hit when it stands next to you due to limited gun depression), one of the fastest things in the game, with an auto-loader gun that fires like a 1911, penetrates almost any armor and deals enough damage to put heavy tanks of higher tiers to shame, who in contrast can't even mildly piss off that scout with a direct hit to the sidearmor. A scout tank that only exists on paper... and you can tell.
Secondly the grind is korean levels. Meaning you're constantly being teased with spending money if you're getting sick of down tiered later war tanks blowing up your Sherman.
Pretty much all tanks are utterly terrible until they are fully upgraded. On the German side, the Hetzer and Panzer IV are some good examples. Once they are fully upgraded, they are decent enough, but holy fucking shit, every minute before that is pure agony. Some tanks, like the Durchbruchswagen, are flat out garbage throughout the entire run.
Thirdly the tier system has and always will be retarded. I get that a M262 would absolutely dominate the skies if you actually unleashed it once you enter 1943, but it's way more unfun to spend time or money to unlock early jets, only to realize you're now facing cold war jets that are going to sodomize you for the audacity to think you're going to have fun in a Meteor.
Yeah, putting tanks into tiers does make sense to prevent the most crazy shit... WoT during the closed beta had only a few tanks, so I had the joy of being the last survivor in my team in a Tier 4 scout and the last remaining opponent was... a Tier 10 Maus in our camp. Not even shooting it in the weakspots would scratch that thing. So there is a good reason to divide things into tiers, but the way how some things benevolently end up in low tiers despite being effective enough at higher ones, while some others are in high tiers where they are just useless... Yeah, oftentimes the decision of what tier to make something are just based on bias. Is it Russian? Better make it a sealclubber, everything else wouldn't be partiotic.
Best example of slav-bias btw: The devs say they wanted to make the game as close to reality as possible, so they look at penetration capabilities of real gun data to use in their game.
If the gun can penetrate, say, 90mm armor in reality, they'll use that in their game. Which would be fine if they weren't assholes.
Slav-weapons always used a 0° deflection as baseline (ie: The grenade hitting at a perfect 90° angle), whereas German guns in their game used data based on 20° deflection (ie: hitting at a 60° angle), which effectively gives them half the penetration power of their real counterparts.
It would likely be far more fun and interesting if matches had a limited amount of certain classes, meaning you can have King Tigers facing a T-34, but the amount of King Tigers you can bring into the fight is limited compared to the amount of mid war mediums.
WoT tried to add a mode like that for years and they could not balance it out.
