My prediction: Preorders are lower for Xbox 360 and PS3 versions because a lot of people are waiting to see what the Wii U version looks/plays like before making a decision. Note that, because it hasn't yet been officially announced (although it has been unofficially confirmed), retailers haven't yet opened it up for preorders, so there's no way to see preorder interest for the Wii U version.
EDIT: Before someone ignorant comes in and calls me names, or anything... I'll point out that I didn't say the Wii U version would sell better. I said people are waiting to see the Wii U version before making their decision on which version they want.







