Wash your mouth out!
"glorified C64-style OS"
If you had said glorified BBC Micro OS I might have let you get away with it! The C64 OS was primitive compared even to that.
But neither had the fluid, consistent, well designed GUI of RISC OS. Sadly, nor does anything else :-(
I keep waiting for someone to catch up with the RISC OS GUI, but after 20 years it doesn't look like happening. It's not going to be Windows with its history of appalling GUI design, Mac OS X did get closer, and while you can change the Linux desktop it doesn't change the apps which all behave like WIndows apps.
Touch sensitive devices or gesture recognition will probably completely change the way we interact with computers, so the WIMP desktop metaphor will be replaced by something "better".
This new ARM hardware will hopefully mean I can continue using RISC OS until that happens :-)