How many ARM-powered netbooks do you see sold in an electronics store chain nearby? Yea, thought so.
There is such a thing as "consumer Linux box"? The one which comes without an admin? This is news to me.
Well, Ubuntu successfully "windowizes" Linux with either GNOME or KDE desktops. Apparently, it does not "windowize" Linux sufficiently enough though, as consumers still prefer the real thing.
See, independently on what you or I feel, a computer manufacturer needs to produce products that sell and do not get returned. Apparently, Linux has worse record in this area than Windows, hence the switch to Windows.