The use of black backgrounds is.....as we all know .....from the "professors" that like to let everyone else know just how stupid they are.... the use of black backgrounds is....welll......frowned upon....
That's really just another fad. Studies* have suggested that on an illuminated screen it is easier to read bright text on a dark background, while the reverse is easier on a reflective surface.
This makes a lot of sense, if you think about how "blooming" works in each medium. On an illuminated screen, overexposure tends to cause the white text to bloom outward into the dark page (which is readable) or to have the bright page bloom into the tiny area occupied by the text (which is NOT readable). The opposite happens to ink on paper.
The style issue here is that people are trying to mimic the appearance of paper. Which works on modern displays, because the resolution is of sufficient quality. But it isn't easier on your eyes.
What I have found to be the case personally is that bright-on-dark versus dark-on-bright text has a strong psychological connotation. The former feels more "informal", whereas the later is more "formal". So personally, I faver bright-on-dark for forums and other informal environments, and dark-on-bright for "official" documents.
Of course, I also have a bias for the old "bright green text on a black background" to mimic the old-style text terminals.
MS said that the only "acceptable" background was.....white..
No doubt you meant that to be ironic, but I'll just be dutifully snarky and say "Yeah, and we trust
everything they say, right?"
*Haven't a clue which "studies", but this is what I've heard from reliable sources.**
**Okay, so it's total hearsay, but I still believe it.