Of course online multi-player is difficult to pull off but with console sale numbers for the Wii U I think the time spent on porting the game to the Wii U could've been used to get online multi-player to work. They spent an estimated 50% of their two years development time on a console that was pretty much a failure at the time the game came out.

The PS4 was well ahead of any other console in sales long before the game was released onto the Wii U. I don't know their exact sales distribution, but I think a better game on PS4 and maybe Xbox One would've sold a lot more copies.