My kids were like 3 and 5 when Kinect was released and they bloody loved it. Also Dance Central was superb for drunken adults.
Plus if Alien Isolation wasn’t scary enough already, a Kinect would dial it up a notch.
Definitely limited appeal and the tracking wasn’t great on the 360 version, but for those first two scenarios (younger kids and late night dancing) it was a superb party game.