The limitation really just forced from one popular meta to making another, which I'm sure was the intention. That they didn't limit Churchills or KV-1s pretty much exemplifies this being flawed logic, but what the hell it changes the game lelic style, right?
All doctrinal units had clear differences in advantages compared to stock units, and almost all of them are either more expensive as compensation, or deliberately sucky but comes earlier and cheaper. Tigers compared to Panthers etc are no different.
If they ninja-changed the game so you could in fact call in unlimited heavies besides King Tiger and Tiger Ace, I'm 99% sure no one would ever notice...nor ever take advantage of it. And before you say "well what's the point then?" I cite their removal of duplicate bulletins: the point is just design decision, nothing more.
Not really, when have you ever seen multiple Churchills and KV-1s be a game winner? The Churchill is not what it was and the fact that they were designated "heavy" in real life means little for a game. Relic will use their own arbitrary rating for vehicles and it makes sense to not limit these. People have to remember historical accuracy is not the way to balance a game.
Yeah, doctrines are where the heavy hitters lie.
I think you underestimate the playerbase. Once a Shock Rifle spammer, always a Shock Rifle spammer. The return of unlimited heavies or capped at two would stop most of the evolving meta, and whilst some people have adapted, you'd get situations where a large proportion of the playerbase is again abusing this lack of restriction or losing to it, with only the well practised who can play around it. It was never fun, it was really boring and medium and light vehicle play is where this game shines.