Re: Compatibility and elephants
"ROX failed for the reason that so many UIs do - not enough support from the app developers."
App developers would probably say not sufficient support for app developers although you go on to make much the same point. Perhaps a GTK and/or Qt compatibility layer would have helped.
I'd also change the emphasis of your last point. Users use the computer do do stuff; don't blame the user base, blame UX designs that get in their way.