Wouldn't that essentially be the standard 360 Kinect bundle?

Well I can only imagine those first party studios will be there to demostrate to 3rd parties what could be done with the new and improved tech and control schemes. And really developers like to see new control schemes, it gives them more options and they have better incentive to make something innovative that could go big and differentiate them from the crowd. But what developers truly want nowadays is to be able to port their games between platforms, and I can see that being a possibility with WiiU's tablet and 720's HD touchscreen. Plus I imagine 720 will have motion controls closer to 1:1 built in, so developers will know that whatever they make WILL be used by everyone who buys the game, so they don't need to make alternate control schemes.

With any new console, you will see a slow adoption and hence 3rd parties will make games closer to current gen towards the beginning. But as some time passes, we will start to see first parties roll out some cool games with the new tech and then the onslaught of awesome quality 3rd party titles harnessing the raw power of the new consoles.

That didn't really happen with the wii though.
And yes porting will be big, but between WiiU's tablet and 720's rumored HD touchscreen? First of all I think there is a very small chance that will be included as standard. And second the performance gap between WiiU and 720 would probably prevent that as well, or at least will not lead to games that can compete with big budget titles. I don't see any Wii+ / Move shared games either.
And ofcourse developers are used to publish on pc, xbox and ps. Only one of those will have the extras.

Next to that I think Kinect 2.0 will be held back at first by Kinect 1.0. Why make your game kinect 2.0 compatible only when there is a 25mil userbase out there that could use it too. The first kinect 2.0 games will just run a bit better, new ideas will come a lot later.

In the end Kinect / Move / Wii+ is all still very risky. Unfortunately the biggest most reliable user base still is the 12 to 24 year old crowd that don't care all that much for alternate control schemes, or paying extra for a standard included kinect.

I think with the Wii though, the problem pretty much was that they didn't have a classic controller in the box, so developers HAD to completely code the game for motion controls because you couldn't just ship a game with a control scheme that not everyone has (same dilemma with Kinect). If the Wii had the classic controller in the box, I think we could have seen a lot more scaled down standard definition versions of big 3rd party games. Plus next gen I don't think the graphic capabilities will be so big that porting to Wii U will be impossible, I mean the Wii U can probably do native 1080p with 60 FPS max which is what the 720 is probably going to be aiming for as well. I don't think you can currently go much better than that. The innovations will probably be with newer more improved forms of controls that we are seeing with Kinect and Wii's tablet.

Also your point of Kinect 1.0 holding 2.0 back is similar to saying why build an xbox 720 when there are 65 million 360s out there? Developers can still build games for Kinect 1.0 since 2.0 will be backwards compatible and these games will be casual stuff like Kinectimals, your fitness evolved, etc. What Kinect 2.0 will do is allow newer control schemes for hardcore games, and later in the lifecycle of the console provide room for making casual experiences as well. So 720 will essentially be a console for hardcore and casual alike, which is what MS has been aiming for as of late.