Third parties are not in a position to demand anything from a console maker, for one. And for another, while Wii U needs all the games it can get, and that is not a disputable fact, Ubisoft if so full of their own shit lately it's not even funny. They are actually making Activision look good by comparison.
Spending the time and money to make a ground up Wii U title (which costs far more, by the way, than porting something to Wii U), and then sitting on it, is actually COSTING them money, and is an incredibly foolish decision. If whatever they've made is a GOOD game, so long as Ubisoft actually bothers advertising it, then people will most likely buy it. Case in point: Zombi U. By all accounts, it's a DECENT game. But it's not a great game. Perhaps if Ubisoft wouldn't have rushed it to make sure it was a launch title, and had put more polish on it, it might have been a better game, and thus might've sold better. Just an idea.