There's a whole load of reasons why it's not coming to the Wii u - or a Nintendo platform for that matter. Third party usually don't sell well on Nintendo hardware, money on development for Wii u hardware, it's on more then enough platforms, Game Freak wanted to try something different, the list goes on and on. The real question Nintendo fans should be asking is why didn't Nintendo offer their support?
If those people want to act like spoilt kids, then they need to grow up.
Back on topic,
I've had an idea. Is there any chance we (as Sega fans) could help push this game? Go out there and spread the word, talk about it on forums, youtube, twitter, facebook, twitch etc and help Sega out a bit more. Be Sega's street team so to speak. I only say this because whenever I go on other sites etc, there never seems to be any buzz around what Sega do. It's like they slip under the radar for most of their products unless it's bad.