I think one of the best things about early 2000-era desktop environments was that it was hard for programs to look out-of-place. In a modern desktop environment, you can easily tell the difference between programs written with different toolkits, like GTK+ and Qt. Even though each toolkit can imitate the other (there's a Adwaita theme for Qt and a Breeze theme for GTK3,) due to the complexity of modern UI themes, it's impossible to get things right and the lack of drop-shadows or animations or hover effects will leave some programs looking sub-standard. On the other hand, every developer can draw a 3D-bevelled grey box. Both GTK+ and Qt apps were made of grey boxes and they both represented each kind of widget in a pretty similar way.
I think one of the best things about early 2000-era desktop environments was that it was hard for programs to look out-of-place. In a modern desktop environment, you can easily tell the difference between programs written with different toolkits, like GTK+ and Qt. Even though each toolkit can imitate the other (there's a Adwaita theme for Qt and a Breeze theme for GTK3,) due to the complexity of modern UI themes, it's impossible to get things right and the lack of drop-shadows or animations or hover effects will leave some programs looking sub-standard. On the other hand, every developer can draw a 3D-bevelled grey box. Both GTK+ and Qt apps were made of grey boxes and they both represented each kind of widget in a pretty similar way.