I've done more than my share of teaching total newbies how to use Windows. There's nothing intrinsically logical or sensible about the Windows desktop (95, 2K, XP), Windows' naming schemes, etc. It's extraordinarily difficult for an adult newbie to pick up. -- We tend to think of Windows as "easier-to-use" simply, I think, because of familiarity. Ditto with the Mac interface -- it's easy to use once you've learned how to use it. Come to Mac from a pure Windows or pure newbie background and there's still a learning curve.
Frankly, I don't think there will ever be a desktop that is "simple to use" from a newbie standpoint (at least until the computers can engage in an intelligent dialogue with the user and actually figure out what the user wants to do).
Consequently, I don't think any great re-imaging of the Linux (or any other) desktop is particularly required. Rather, I think the greater value will be in continuing to support a diversity of desktops with some focusing on new-user needs as much as others focus on the needs of sophisticated users.
After wading through four levels of menus on a default KDE install, I wish I had the skills to do some interface design myself. Grin.
Science is what happens when preconception meets verification.