I know, but it's not just about being built in or not anymore. Assuming Sony doesn't go third party next round, it would be fair to say games will still be developed on multiple platforms, and as long as these multiple platforms provide different motion control solutions you won't see any being supported to its fullest potential by the industry due to the need to stick to the lowest common denominator. Hence the only games that would be really benefit from Kinect2/Move2 would be exclusive/1st party ones.
I'm with you on that for 3rd party games, just like how in this generation developers have had to develop for the lowest common denominator of non-HDD consoles. But, exclusive first party innovation could still push the platform. Some guy snarkily replied to my comment about SOny making a half-baked add on (Move) by mentioning the Dual Analog controller for the PS1, released in 1997, and while his point is lost in a discussion about innovation 15 years later, the Dual Analog controller is a great example of how console exclusive games can push the technology for other consoles.
A great example is Ape Escape, which came out shortly after the dual analog controller was released in the states, and it was a premier PS1 title that was so unique and really pushed other developers to realize that they needed to support 2 analog stick control. Next thing, major 3rd party developers were releasing content on the PS1 that supported the dual analog controller, and it pushed future console development to universally support dual analog control.
I feel like developers like Bungie or Turn10, who are totally invested in the Microsoft ecosystem, are scared to develop around the Kinect just because it wouldn't have widespread adoption and the game would only sell to Kinect owners. But if Microsoft did built kinect functionality into the next console, in some way (even if it were a competatively priced launch bundle), then you'd see more of those mostly exclusive developers taking chances, which could really push other consoles and other 3rd parties to jump onto it.