...when you release a brand new system with specs that are equivalent to the competition's 6/7 year old hardware. The main market for the WiiU has had a PS3 or Xbox 360 for years now, and the WiiU offers no great reason to upgrade. The screen-on-the-controller gimmick is interesting, but not enough to justify dropping $300 on late-to-the-game also-ran hardware. These gamers are all waiting for the new Xbox/PS systems. Nintendo should have released something with more horsepower, and gotten a jump on that. And the casual market for console systems is dead (or, at best, they're all content with their old Wii).
Nintendo is a company with a history of massive successes and blundering missteps. The WiiU is in the latter category.