Siege Ladders and Towers are incredibly weak and easy to kill. The reason people don't make them is because it is just easier and makes more sense to destroy the wall rather than try to scale it. If the enemy good player has made a bunch of defensive towers around his wall, then siege ladders/towers become utterly useless. Your units will mount the wall just to be slaughtered by arrows. Instead of nerfing evil siege, there should be some options added to strengthen good defence. Gondor doesn't really need anything, but Dwarves could use some defence upgrades, and Rohan needs wall mounted catapults badly.