And players would still be able to use ladders, rams and siege towers to try taking the city without bombarding it first. Although the amount of casualities would be much higher, it provides the player with an interesting question; assault quickly and face the consequences, bombard the walls for an easier assault or starve out the defenders. Add a simply supply system and you've got a far more accurate medieval wargame.
Edit: by the way, this is also partly possible already with R:TW using scripts (damage_wall). Just to show how close CA is to such a system.
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