And really, folks who have complained have been the minority anyway. For us anyway.
You may personally feel that light-on-dark is better, but your visually-impaired users will disagree. This includes a huge number of older users, as eyes deteriorate significantly with age (even among people in their 40s and 50s).
Also, you have no idea whether the complainers are in the minority or not. The people it bothered probably didn't stay long enough to figure out how to complain. Do you get compliments from people who say that they're glad you use light-on-dark?
1. http://graphicdesign.stackexchange.com/questions/15142/which...
The inventors of CSS have failed greatly.
Also, should we assume that the people have their vision uncorrected?
I think that black on white is just a fad, perpetuated by following conventions. Like glossy screens.
For a bunch who calls themselves as "nerds" and "geeks", the HN crowd is becoming pretty dumb lately..