Great article, Patrick. This sums up how I've felt about motion gaming since its inception.
Specific to Kinect, however, was the cost it was asking for the consumer to assume to try a genuinely new product. People really glommed onto Wii motion controls not because they were great, but because the cost and barrier to entry was low next to the Kinect - it came straight from the box on day one. The Kinect was priced high for an accessory that supported only a handful of games and, when it was released, the 360 had been on the market for so long that the game-buying public brought expectations to that system the Kinect was never going to fulfill.
My parents LOVED Wii Sports, but when we introduced them to Dance Central, they asked me how much it would cost for them to get this game at their home. When the cost was too high, they opted not to get it. I ended up sacrificing my old Wii (Wiimotes and all) with an upgrade to the WiiU just so they could play Wii Sports...and I suspect I will never find a reason to buy 4 Wiimotes and install a sensor bar ever again.
When I get the Xbox One, I'm going to opt out of Kinect. Dance Central is a compelling franchise, but it's the only mainstream Kinect product that ever had any traction...and I'm not paying that Kinect toll for just one game more than once.