Linux can do whatever it damn well pleases. You can take Linux and turn it into the most feature-poor "easy-to-use" toy on the planet, as Google has demonstrated. The UI has little to do with the underlying technology.

The problems with the Linux desktop that I can see are poor driver support and a limited software selection. OEM support solves the driver support problem and Chrome OS demonstrates that people are willing to use a system with no software at all. What else makes it unsuitable for most users?