Wasn't that a selling point? That it would NOT be a gimmick because developers would know that every single person had a kinect so they would take the time to incorporate it. By late 2015 there will probably be more kinect-less models than with kinect out and then what reason would developers have to take the time to to involve kinect in their ideas.
Then they went and changed game system to PS+ after everybody was saying PS+ was no different than renting games because you can't keep them.
Now couple in the fact that the Xbox One didn't make the power jump the PS4 did is a 400$ Xbox One even a better deal than a 250$ PS3?
Kinect will still be around, appealing and viable.
You could say the same thing about the Kinect for the 360, whats the difference? They aid you can still do the side snap and instant switching so you think people will pay an 100$ to be able to do those things with their voice?
The kinect is back to being an accessory and everyone who bought the original model was tricked.