Because originally it was for PS3 and 360. used Relic Engine but then they went out of business. THQ picked up publishing rights and was on Darksiders II engine. THQ went out of business. Nintendo like they did with Bayonetta 2 swooped in saved the game and said they would publish it. Now it's on UE3. So like Bayonetta 2 if not for Nintendo the game would not exist.
I find it funny when ever MS or Sony publish something people either cheer or don't react. When Nintendo does. "why is this not on console X or Y?"
Well that's only cos it's better suited to the Xbox. That's where the action whores live. I understand the reasoning though. Given that the game was well under way, it was an opportunity for Nintendo to get an exclusive game at a lower cost than it otherwise would've been.