There is more to getting a good dekstop then just doing the 'make install'. A userfriendly desktop must provide all-working functionality as well as the normal set of expected functionality.
Something like that. It's a total package thing. Just providing working software is a first step.
The trick is that whatever it takes Debian hasn't been able to do it. If Debian had the ability to get good default configuration out to users on a timely basis then there would of never been any need for Ubuntu in the first place. There would of been no market for it... people would of just used Debian.