This 'interactive' stuff tends to get marketed towards families and kids who are 'intimidated' by controllers, but there's a lot of possibilities for more mature gaming experiences. Imagine meeting, instead of a benign little boy like Milo, a really sinister GTA character and actually making the motions to breaking into a car or loading a rocket launcher. Sounds cool to me, but the quick scan technology is a little more than scary...imagine walking around a GTA-like world or a Silent Hill or RE universe and seeing your own face reflected in an in-game mirror.
EDIT: In case anyone missed it
https://e3.gamespot.com/press-conference/microsoft-e3/