Make that the siege towers and catapults can be moved only by a few players, not by one, like it's happening now. It's funny that one player can move alone a huge tower. It also will complicate the "stealling" of this equipment by the enemy. Let's say that a catapult can be moved by 2 players, a medium tower by 4 and a big tower by 6. One player still will need to press the Move button, but the siege tower/catapult will start moving only if there's the necessary amount of players near it.
Thanks.