However, I desperately need a professional, stable, feature-complete, mostly bug-free workstation GUI with modern capabilities at least as good as Win2000/XP, Irix, NeXT like I had 10+ years ago.
Something like Xfce polished to OSX-level quality.
If one of the design-goals is that "menus are too difficult" there is no market available for that product. The people that would benefit use Windows, OSX, iOS, and Android already.