Steve has mentioned to me on a couple of occasions his surprise that the XBox Kinect hasn't had more hype about it compared to the Nintendo Wii upon its release; the reasoning, technologically, the XBox Kinect is more impressive with its body/voice recognition than the Nintendo Wii's Wiimote gestures. I agree it is. However, it's not surprising that the degree of hype isn't the same.
Blame it on jadedness with peripheral-based games or a glut of games following the "causal gamer" market. Whatever it is, expectations have changed since 2006 when the Wii was released. In 2006 there was an untapped market for gamers who were left behind the learning curve that kept growing long past the re-emergence of video games in the latter 80's. Nintendo had understood this from the shrinking video game market in Japan. Sony & Microsoft are just now playing catchup with this now-fully tapped market; along with numerous peripheral Wii games, portable console games, smartphone games, pointless money-making Facebook games, iPods/iPads app games, a plethora of [Your Musical Instrument Here] Hero& [Your Music Genre Here] Band games, the Playstation Move & XBox Kinect are now on top of a massive heap of battery/time sucking casual games.
Most casual games, from what I can see, aren't too much different from games that have been around long before '06. The graphics are prettier and there is a wider variety of different types of controls, but the fundamental mechanics of the games haven't changed that much. Casual games haven't done anything to push the limits of what we know as video games, it has rather just reiterated what has already been great about video games. To use the tired Hollywood analogy, they are mediocre 2nd-rate shows and movies; not anything awful but not anything spectacular either.
Innovation with video games will always take place with games aimed at the hardcore (or "core" as I've seen it recently) audience. Why? Because its these games that focus on the real meat of any video game, the gameplay. The audience is assumed to have a certain pre-existing knowledge of video-games and is apt to picking up new and different ways of playing video games. Thus the creators are free to experiment with new things;things that lead to innovation in video games.
As great as Nintendo Wii, XBox Kinect, & Playstation Move are, they will never supplant the core gamer's trusty friend, the controller. The reason for this is the controller allows for greater precision and less ambiguity between the gamer's intentions and his performing the mechanical action to follow his intentions. I think about this in terms of a less-used (but still abused) sports analogy; if a company produced a simple one golf-club that worked for any situation and allowed novices to get further distance than with a normal club, you'd never see professionals take to this club. Why? They wouldn't want to sacrifice accuracy for simplicity. A professional understands all the mechanics, variables, etc, in the game or sport he plays. Any value gained by easy of use would be sacrificed at the cost of loss of control.
In terms of video gameplay mechanics, many of these motion-based controllers do the same thing. Sure it's easier to realize how to do a punch or kick in a motion-based controller. But ultimately, some computer determines whether that motion you performed was a kick or punch. Computers are superior at making binary choices–either a button was pressed or it wasn't–when it comes to making fuzzy decisions (e.g. does the certain movement of the leg joints represent a kick) the results are not as good. Thus, motion-based controllers will always sacrifice accuracy at the cost of ease of use. The day motion-based controllers replace the standard videogame controller is the same day all sport referees are replaced with computers; it's not going to happen.