Well, to be honest, the GUI has had one heck of a tweak since OS3.9
The problem is that those programs you mention all run MUI, which is a third party Graphical interface. Reaction in OS4 has had and is having a major overhaul.
When new applications come out, I am sure there will be a major improvement.
I can change the AmigaAmp skin to any available for winamp, providing I have the correct datatype. I just can't be bothered
Apparently, I could also (so a fellow amiga user tells me) have run four Movies on my Amiga AND run Q2 on top, which is what he did on his G4 processor equipped AmigaOne.