Microsoft ruined the Kinect by forcing it on gamers at the beginning of this generation.
The mandatory Kinect just led to many gamers shunning the One, and a lot of people refused to buy it because it raised the price of the console.
Microsoft had no Kinect games that really stood out ready by launch, so the only use the Kinect was getting was as a navigation tool and webcam (for the most part), making it hard to justify the $100 price hike.
Due to all of this, the Kinect has been getting a lot of bad publicity, not for being bad hardware (it certainly isn't), but for taking away gamer's abilities to choose for themselves what they like. In short, it became the symbol of the Xbox One's shortcomings, even though it may not have deserved it.
Now, with the Xbox One available without the Kinect, it is obvious that a lot (if not most) gamers will choose to forgo the Kinect and save a hundred dollars, especially since it got all that bad publicity. And since most gamers won't be using Kinect, game devs won't be making worthwhile games for it.
Microsoft doomed their own innovation by making it mandatory. All it did was push gamers away from it, and by taking it out so early gamers will never fully accept it either. If they had demonstrated its power through innovative games, and gave their customers a choice on whether to get it or not (like the Kinect last generation of Morpheus this generation), the Kinect may have done a lot better in the long run.
You're Gonna Carry That Weight.
Xbox One - PS4 - Wii U - PC