Remove Building check from setting up siege engines

[Walrus Warwagon]

Default ballista is barely useable with how heavy it is and how little damage it does, and catapult is almost unusable with how heavy and bulke ammo is.
They are still interesting piece to use to enrich the roleplay. To set them down it was enough to pass the engineering dc. Now it also requires a building roll.

Does it really adds anything by making complicated things even more complicated?