> When the Kinect launched, Microsoft had trouble getting a critical mass of players that would attract developers

Developers generally disliked it. It just didn't work well as a game controller.

The Wii was much more practical. You still had a controller in your hand with physical buttons, which makes a big difference, and it worked as a fairly accurate pointing device. Those more than made up for the limitations of accelerometer-only motion control.

In the early Xbox One days there was a lot of experiments with hybrid controls where you'd still have the controller in your hand, with its accurate joysticks and physical buttons, but have the Kinect sensor for body posture and facial expression and gestures out and away from the controller (and voice recognition). The SDKs had a bunch of interesting things about controller recognition matched to other data. The OS itself would do things like pick out which controller a specific person was holding, and could use that for sign in (among other things). The Xbox One dropped the "controller number ring" from the 360 because it could tell what person was holding the controller rather than needing to signal vice versa which controller a person should hold. There were some interesting Kinect party games that took advantage of this or nearly took advantage of this (hybrid games where maybe everyone would set down controllers for a mini-game and it wouldn't matter that everyone picked up "the right" controller back when the next controller section started).

In the end, couch coop that was pretty essential to the 360 just kind of withered away in the Xbox One era (when games like Halo competing on looks with other consoles decided they couldn't afford the frames/resolution costs of split-screen coop anyway) and that missing "controller number indicator" no longer mattered in the end, but in the original plans of the Xbox One the hybrid Kinect/controller gaming support was key to things like couch coop.

It's still interesting to wonder about that road not taken if more developers had considered Xbox One hybrid Kinect/controller controls more seriously beyond just the few experiments we did see.

> That device is SO much more engaging and approachable for kids than trying to teach them to use a controller.

I dunno. I had the original kinect for the Xbox 360 and the controls were wonky. A controller might be weird for a few hours but especially kids should be able to pick it up quickly and then it does exactly what you input, unlike the Kinect. However, I have watched multiple girlfriends struggle with 3D controller input so maybe it's just not for everyone and has nothing to do with kids?