Despite its success, it still had a lower attach rate than the Famicom Disk System. In terms of software, after the first year no one could make any good money selling Kinect titles.
> Kinect for Xbox 360 continued its momentum in 2011 reaching 10 million Kinect sensors sold worldwide to date. Not only were sensor sales an overwhelming success, but Kinect drove significant game sales with more than 10 million standalone Kinect games sold worldwide to date
From 2011. At any rate, it obviously satisfies the grandparent’s comment on success. (Also, you may be thinking of the Xbox One, which they received flak for bundling with a Kinect)
Microsoft knew add-ons simply do not work long-term. That's why they put a Kinect in every Xbox One's box. Didn't solve the problem of everybody was over with the concept though.