This would be great. Also, I think when fighting on a mountainside or something similar, rather than generating a lot of small, steep hills, a better option would be to make the entire map sloped in one direction or another. Likewise, I like the idea of a forest thick enough you wouldn't be able to ride horses through it and the fighting would have to be done on foot. And some seaside battles would be pretty cool too. Even better: skirmishes on coastal cliffs.
One thing about the bridge battles, though. Unless the bridge was over a very steep ravine with a river at the the bottom, it wouldn't be much of a choke point. Rivers can break a cavalry charge, but one can still cross over them quite easily. If some rivers too deep to wade across were implemented, this would work better.