Smartglass is a "smarter" way of implementing the idea, but again- the Wii U is a whole bundle. It's the whole shebang. You don't need to buy a tablet or a smartphone to hook this system up- it's all there for you. And it's probably going to be way cheaper of an investment, when you factor in that casual gamers have all their wii remotes, balance boards, and whatnot, now all they need is this bundle that will undoubtedly be cheap (cheaper than a Kinect/360 bundle, most likely), and more accessible.
The Kinect may be a cool piece of tech, but I just don't see it having "hardcore" basis- and Nintendo has at least established that motion controls can go hand-in-hand with core gaming experiences (the FPS was really the first of these to succeed, Zelda was another proving ground) while pretty much all of the Kinect "core" games have been wonky as hell.