Wii U has a big number of problems. First, it should not have been called "Wii U" and it doesn't have looked as much like a Wii as it does. The fad of the Wii is over. Those ultra-casuals that bought the Wii moved on to smartphones and tablets years ago, and that demographic is about gone. Wii had the fortune of launching before smartphones and tablets really took off, but the Wii U doesn't have that. So who's left? The core gamers. Core gamers don't want a Wii. They want first-person shooters, action adventure games, sports games, realistic art styles, etc. It's good to have the family games too, because younger people still like games, and some adults don't like the stuff I outlined above.
But that's what sells! Nintendo doesn't make that stuff for some reason. They stick to their old franchises, which are no longer the instant blockbusters they used to be, and they need to diversify their game lineup. They need to make the Wii U a better media player. They need to get serious about online functionality, starting with a real account system where games are tied to your NNID. They need to make the interface not look so Wii-like. Honestly, I would be all for them getting rid of Miis, at least on Wii U. There's so much they need to do, but if feels like they are trying to make a more traditional console... but for the ultra-casual gamer who has long since forgotten about consoles.
I want Nintendo to succeed, because I really love a lot of their games, but it's really hard for me to support the Wii U.