I agree with most of what you said here, as well as with the notion that fun should trump realism every time. But I come to a very different conclusion than you.
Recently, my most played vehicle in game has been the Jagdtiger. Many reasons why I love it, which I won’t get into now, but one of the things I find very rewarding about it, and really 6.7 in general, is that shot placement is incredibly important. A big tank destroyer with a giant “f you” gun would basically be able to click and pen almost anywhere at lower BRs. Not so here: either you meet light vehicles that require you to aim your APHE for crew location (less they simply overpen and pass through without damage), or you meet enemy mediums (let alone heavies) with lots of sloped armour that you can’t just expect to lolpen. You need to memorise weakspots religiously or you’re screwed.
This is even truer because in the current “meta” (god I hate that word), heavies are at a severe disadvantage. This is a balance problem that I hope gets rectified soon, and the recently announced decompression is a good step, but still, generally speaking: if you have an 18s reload, and you’re usually pitted against opponents with autoloaders and greater pen than yours (if lower postpen damage), you need to make every shot count. Period.
This is where I come to bushes. First defensively, and then in terms of the shooting skills and weak spot memorisation we’ve both been talking about.
Defensively, bushes make my Jagdtiger a lot more viable. They’re part of the layers of security onion, beyond just relying on armour. “Don’t get spotted/hit” is always the first, of course, but in a prolonged engagement - especially if you’re 1v2 or 1v3, you need to stay alive in-between those 18s of reload. That means angling between shots, wriggling unpredictably in place, moving the gun so you don’t get barreled. And good bush placement also allows you to survive far more often in these situations.
This is true for all heavies, and some more than others. Tiger II P is a completely different tank now that I’ve bushed it up. And lol, the Sturmtiger, don’t even get me started :D
Mobility is always an advantage. This is especially and acutely true in a game built on capping points. Armour is always a disadvantage, and quite literally dead weight, up until the point that it actually guarantees a bounce. And while you can mitigate the lack of armour in a variety of ways; you can’t do much to mitigate a lack of mobility.
Vehicles that sacrifice everything for armour protection (they’re slow and have either mediocre guns, or good guns with long reloads) can’t actually benefit from said armour protection, if the game is balanced in such a way that even very light and fast vehicles can cheese their way through your frontal armour. This is why, while many people have rightly the image of an invisible bushed-up ASU 57 or AML in mind, I’d argue that the biggest beneficiaries of bushes are actually heavies, even more so in the current imbalanced situation that greatly penalises them.
(Of course that is realistic, and the reason why heavies went away IRL, but like we’ve established, fun is more important than realism, and there’s no reason to have a vehicle in game if it is not competitive).
Now, let’s come to the question of bushes from the offensive perspective. You say bushes nullify your skills of ID’ing the tank and having weak spots memorised. I agree to an extent with the former, but not with the latter. Countless times I’ve spotted, say, a bushed-up IS tank at a distance and wondered, is that an IS-3 or an IS-6? Obviously that is a moment of indecision, because while their respective weak spots to an APHE shot are somewhat similar, they’re not exactly overlapping. But you can aim for the tracks or the gun, and do real damage, while also knowing that the “hit cam” will show you what tank you’re engaging (even in simulator!).
And once you know it… you can still aim for the weak spot. Yes, the tank is covered in bushes, but you’re familiar with its proportions, size… and when you get it right, it feels incredibly rewarding. One-tapping an IS-6 absolutely covered in bushes at 1600m through the gun mantlet weak spot at Sands Of Sinai is an amazing dopamine rush. And just as skill-based as locating and hitting the same weak spot on an IS-6 without bushes, in my opinion. :)