One reason Windows sells so well is that the user doesn't need to know squat about the operating system to install something new. See a cute new program? Whee, here we go, one click, none of this save to and chmod business.
In response, there are Linuxes now that habitually run as root. They are dummy friendly. And dangerous.
There are two categories of Linux run-as-root.
There's the standard installed-to-the-harddrive kind, of which I only know of one, Linspire. And even with running as root, it still won't execute binaries that have been downloaded without setting them executable first.
Then there are the Live CDs, most of which run as root. But you can't infect them with spyware.