"As MacOS X (and GNOME to a certain extent) has shown,
many people love photorealistic icons despite the theoretical
trade-offs with usability. So if you've ever wondered about the
philosophy behind KDE's default icons, you might want to read
Torsten Rahn's recent article on the matter. Tackat explains how
KDE's default icons are a compromise between good usability and
beauty, using a mock up of traffic signs to illustrate his points.
To conclude, Tackat proposes a slightly different approach for KDE
3.1: Add more photorealistic design to the application icons, while
sticking to 2D for toolbars and mimetypes."