First of all it has nothing to do with all that extra crap that Microsoft and Sony's console can do........I personally never use my console for anything but gaming, i have never watched a movie or streamed anything through my game consoles, i play games and only games on my consoles, and i still wouldn't own a Wii-U.
The Wii-U hardware is a generation behind, if that isn't bad enough, that tablet game pad of theirs only lasts about 3 hours on a full charge, the pro controller they introduced, not only doesn't work with most games, but the Wii-U tablet controller must be powered on to use the pro controller.
Most people don't even know about the Wii U's existance thanks to Nintendo's terrible marketing, even at the 2011 E3 everyone didn't know what to make of their press conference, most thought it was a new tablet controller add on for the Wii, because they never talked about the console itself.
Once again Nintendo's online strategy falls waaayyyyy short of the competition's and it's nowhere near as easy to join games, chat with friends and just play online in a community....it's too complicated.
Put all that together with the lack of 3rd party support of the Wii-U's first year, and that is why it's failing and why it will lose to PS4 and Xbox One, because Nintendo is stubborn and cheap, they made billions from the original Wii and DS hardware, and could've easily put together a console that would have rivaled PS4 and Xbox One, but no they had to try and innovate yet another control scheme, and now it's back firing all over them, they refuse to follow any trend in the gaming market place, they just want to always do their own thing.
Well now it's costing them millions in sales, and no amount of 1st party games is going to save the Wii-U against the PS4 and Xbox One.