Another Wii U post, eh? Just read the Shokio thread, and bah gawd king.
Marketing has always been the Wii U's problem.
Don't let know-it-alls trick you into thinking otherwise. I've said it before, most casual players and parents must think it's a $300 Wii add-on to go with balance board and the rest of them. The gamepad is always the main focus, with the actual console sat behind it. Advertised like "Oh, you don't need your home television with this latest gimmick, play all the games on this new fancy portable TV that doubles as a controller". Sharing the Wii brand doesn't help. I understand that by stamping the Wii name on the console they may have thought that it would guarantee instant success. But oh well.
The console's poor sales have nothing to do with the system's power, look at the Wii, it never supported HD, had laggy online, none of the social features that the PS3 and 360 had, and nowher near the power either, and yet it trounced them both in sales thanks to marketing. It never needed GTA or Jack Tretton to tell you what to play. There were even stories of pensioners in retirement homes playing them and obese fuckers using them to get fit.
The novelty of the Wii wore off a short time after people bought it. It was billed as a fly-by-night fad, and I think that's why now, the PS4 and XOne are selling better. As most players now must think that they'll get more use out of them in the long run than a gimmick console. Even though the Wii U is a fantastic machine and the console that the Wii should have been.
There are other, smaller issues as well. Like the fans. The majority of Nintendo's current fanbase (or at least the most vocal fans) aren't the most welcoming bunch, they're a group of elitist hipsters who'll launch a nuclear attack if you dare say anything even slightly negative about Nintendo. Doesn't matter if you've been a fan longer than they've even been born, they're just so standoffish and ignorant to people online, and it could be seen as a turn off, especially to those suddenly rallying for voice chat. This isn't an attack on Nintendo fans either, I am one, this site has some great fans, just a shame that the good ones are drowned out by fedora-tippers.
Lastly, you don't buy Nintendo consoles to play third party games, you buy them for Nintendo's own first party content. I mean they've got the backing of PlatinumGames, Koei Tecmo, the great Tomonobu Itagaki, and more, and that is great third party support. Just because Ubisoft have fucked off doesn't mean all is lost.
TL;DR Read it, lazy.