People aren't stupid, they're lazy. They expect things to just work out of the box. They don't want to create online accounts,they don't look through the setup menus and they certainly don't read the manual.
I think the point is that Kinect is only part of the package. Nintendo delivered the full thing with the Wii: a friendly, non-gaming-related name and brand, accessibility with the Wii Remote from the first minute you turn it on, a low price point, what they call "bridge" games (games designed to get hardcore and casual playing together, like Mario Kart - unsurprisingly, Mario Kart outsold and continues to outsell games like Wii Fit), etc. Kinect just provides casual games and a UI for those games.
There needs to be more, and hopefully Microsoft will grow in that direction. Obviously their decision right now was to spur the growth and sales of the Xbox brand for the next few years by releasing Kinect as an addon instead of a separate device, but there was a lot of wisdom in Nintendo's move away from the "Nintendo" people associate with 80's videogames and Super Mario.