I wonder if the game didn't sell as anticipated on the other platforms and they don't feel like they can make any sort of profit on Wii U either so they're just giving up.
Or they just don't give a shit either way. Whichever one.
It's been riding high in the charts. Consecutive No1s in the UK and I believe the PC version has done well too.
I think it's more, they don't feel at this stage there is any point devoting lots of additional manpower to a Wii U version that'd likely sell tens of thousands.
For all the people saying Lawsuit. Nobody paid ANY money towards a Wii U version of the game. Anybody investing money in this was investing to GET MONEY BACK.