I'd agree with the point you raise that most users would consider themselves "experienced", especially within the terms stated by Matt Edgar.
Thing is, though, is that this is a terrible shame. RISC OS computers work out of box. You have an operating system that doesn't need *any* preliminary installation, is almost imporrible to corrupt, and acts in a logical, consistent way.
My Iyo, out of box, supported Email, Internet browsing, dtp and spreadsheets and CD writing. Add in DVD and video playback, and you've got 95% of computer usage.
Having had extensive experience setting up and fixing other people's computers, RISC OS is a dream to work with. Sure, it could be improved a little, made a tiny bit more user-friendly, but in general, I find it's one of the easiest OSes to use, and the support is fantastic, and easily accessible.