Reverie has been saying for a while now that the graphics are not final anyway - they still have to update them.
With wall-mounted siege engines having farther range [which makes sense] the besieger would have to bring in significant numbers of siegeweapons in order to take out the defender's. Also, one of the Reverie people commented on a post of mine saying that siege engines will be limited by their inaccuracy. They will not be able to pick off moving targets at will. Think of Trebuchets in AoE2 - very effective against castles, towers, walls, and buildings, but completely useless against units.