I agree, I hear people talking about siege equipment all the time, yet I haven't had the pleasure of seeing any utilized in a strat battle. The utilization of cannons in mm mod was really cool, perhaps the same can be applied to C-RPG. Furthermore, how hard would it be to make destructible walls, or just keep the destructible gates and use siege equipment? I, for one, would love to see a ram in this game. Same mechanics as pushing a siege tower, but destructible (so defenders can try to sally forth). What you are suggesting would require a great deal more teamwork than is currently implemented. If people get touchy about deployable ladders, then keep placed ladders. Finally, some defensive/offensive siege equipment against men would be great. For example, hot oil, catapults, ballistas, caltrops, ect.
Thanks for the great suggestion!