I think you got to understand the limitations of the engine on which this game is built on. It seems to me to make larger troop amount they would probably need to create an advanced barracks in which to do it.
Also this game is built on flash which, if not dying, is definitely in decline compared to the now more popular HTML5. As a company it would make a lot of sense for BB to start pulling resources out of old technology.
Does anyone know if Anno is also flash?