The Wii U has been defeated by the most humbling of challengers - consumer apathy. When the inevitable "Nintendo halts Wii U production" stories hit, the majority of those that bought the original Wii won't even notice. The mainstream bought the Wii because it was a fun novelty, they didn't buy it for a new Zelda game. What's the Wii U's novelty? That it does everything a current-gen console does but a little bit slower and with a Fisher Price tablet attached?
Why was the original Wii successful? The Wii controller was the first commercially successful motion control system. There had been many, many attempts at motion controls, but the Wii was the first to catch on. The controller made the Wii extremely accessible to non-gamers.
I remember using an original Xbox controller after nearly 10 years out of console gaming. The last controller I'd used was an original NES with nothing more complicated than a D-pad and two buttons.
While I'd been out of console gaming, I had played some games, including some FPS games like Marathon, which I played with a mouse and keyboard. But I sucked at using a controller to play Halo. I couldn't shoot, I couldn't duck, and even if the game physics would have supported it, there was no way I'd have the coordination to pull off something like a grenade jump, which, since it was almost mandatory for reaching certain parts of Marathon maps, I'd gotten good at doing with a keyboard and mouse.
I spent a good part of the first couple of weeks being terrible at controlling my character. I liked games enough to keep playing and got better at it, but most normal people would have given up after 5–10 minutes of dying a lot.
The Wii controller flattened out the learning curve enough to make it easy for both young children and inept adults to pick up a video game and just start playing. Similarly, touch controls feel intuitive after a brief introduction period, which is part of why iOS games have done so well. The game types were perfect for the controller, with a distinctive style that Nintendo had refined on earlier platforms. The games felt like they had been created with the controller in mind, and indeed they had been.
What does the Wii U bring to the mix? Nothing focused, and that's the problem. In an article last year, I had doubts about the lack of focus, and recent events have shown that while there are plenty of tools on the Wii U controller, there's no coherent hook, no holistic approach to using these disparate abilities to create something compelling. Nintendo itself doesn't seem to have been very successful at creating a suite of games that exploit the capabilities of the system, unlike the handful of first-party games they released alongside the original Wii.