In a Reddit Ask Me Anything (AMA), a Microsoft developer (speaking anonymously) released an interesting statement regarding the Kinect and how it may have affected the Xbox One's price point.

The majority of the masses care only about the console,Except that the success of the Kinect carries much more weight to us. The sensor costs almost as much as the console to make.

Assuming this is true, it would certainly explain the price point in comparison to the PS4. Also, is the system even profitable at $5oo? The developer also explained the decision to include the Kinect with every console.

The goal with having a Kinect ship with every Xbox is to guarantee to game developers if they implement Kinect features into their games, everyone who has an Xbox will be able to experience it. I often see people dismiss the Kinect instantly because they haven't seen it work like I have. It is an integral part of the Xbox One experience.

This is direct opposition to the Sony's approach, as rumors have floated that they cut the PlayStation Eye camera to undercut the Xbox One. Was Sony right in this decision? I believe so. Motion gaming has yet to be embraced by gamers, and I really do not seeing it being embraced anytime soon. However, credit must be given to Microsoft for putting their money where their mouth is with Kinect. Now we wait and see if it'll pay off.