I remember hearing once that a dark background is less fatiguing on the eyes than bright, because a computer monitor emits light. A lot of the old programs like AutoCAD and early Pro/E used a black or dark blue background, and I'm guessing for this reason? For some reason, SolidWorks has never done this, and now, the newer versions are using a REALLY bright scene as the default (3 point faded).
The problem is that there's not a really easy way to change to a black background without losing something (like black text in the integrated feature tree, etc...). Does anybody run a dark background color scheme or have any tips on how to switch easily?