This is a good decision. Not only from a price perspective, but also not forcing a terrible control scheme upon people. Give consumers a choice whether they want to put up with that headache.
Movement controls are crap. They're still crap, don't be fooled by slick fake presentations. Kinect was THE worst thing to happen to gaming on 360. Developers lost focus for exclusives and wasted resources trying to get the thing to work with new games.
By packing the Kinect2 and making it a requirement with the XB1, not only is MS putting their turd in every box AND making consumers pay $100 for it, but they're forcing it down your throat too. And it's going to end up creeping into even more games. Fantastic.
If MS is smart they will announce a Kinect-free SKU for $399 at launch. It would make for an extremely competitive holiday season that's for sure.
