I get the feeling honestly Ubi Soft really doesn't want to make a Wii U version, but since they already commited to it, they don't want to look bad to Nintendo because they sell a good number of Just Dance games on the platform (at least the original Wii anyway).
I don't think they really give two craps about getting an extra 30,000 in sales from a Wii U version though. That's the last thing on their mind.