Last time i wanted to play some building maps, i indeed went to siege just to face 3 plains maps in a row there (yeah, was temporary as they were sorting new list of maps, Punisher explained that to me in other post), but it still happened, so your "go siege" argument is rendered invalid. HA!
Also, some people might not like the siege idea and preffer battling (for instance: me).
I do mostly play infantry, i do not mind having to suffer thru some plains maps once in a while (suffer only if i play alone or with just a few reasonable people, if there are good people who knows what they do and/or some clanmembers, its difference), but i am getting tired of the cav lobbying for more and saying: Just do teamwork. Yeah, it is REALLY easy to organize crowd and both you and me know, that most of the pubby players will never listen to what you write and just headlessly charge/camp something.
Never expect anyone on the battlefield to help you or to play strategically, unless you know the people. ofcourse there might be some exceptions, but face it, not many.
What the people also seem to forget: we have several classes, each class enjoys different type of maps. There is plenty of space for cav on most of the village maps, so...