The destruction of buildings was made to emulate the looting that always followed battles... Even the best commanders had trouble stoping this once the battle was won.

If they manage to stop it, was because their dread was high enough to scare the living pants out of their own soldiers.

In the game, if you had a way to disable building loss, you would have end up losing the realism in the association:
War=>destruction=>lower tech
Peace=>Money money money=>construction=>higher tech