[celrod]

I regularly get migraines, where "bright" lights are searingly painful to look at. When the symptoms aren't too bad, dark themes on a text editor are okay, but light themes are not.

Migraines aren't an uncommon problem.

I think that is a fairly objective reason driving the preference.

[codedokode]

I dislike sites with dark background. Maybe it is a problem with my poor quality LCD screen, but I switch to reading mode on such sites (so that the background becomes white) because they are hard to read.

[beatgammit]

I'm pretty much the exact opposite. I typically use my computer/phone in a low light environment (monitor and phone are almost always on lowest brightness settings), and a white background hurts my eyes. I use a dark background wherever possible, especially when reading ebooks/longer articles on my phone.

Any good software designed for reading should have good support for both.

[ncmncm]

Conceded.