I cannot comment on developers' preferences as a whole, but I personally have several large floaters (https://en.wikipedia.org/wiki/Floater) and using a display with a bright background makes them very noticeable and distracting. Which is why I use Dark Reader (https://chrome.google.com/webstore/detail/eimadpbcbfnmbkopoo...) for websites and dark themes in my OS/terminal/IDEs. It's not just an aesthetic choice.

For me, eye strain, and being more of a night owl (where it gets dark outside during winter).

I favor Solarized, which has both a light and dark theme: https://en.wikipedia.org/wiki/Solarized_(color_scheme)

I prefer consistency. The system setting, is the best here. If my system is dark, go dark, if light, go light. At night, dark is great, in a bright room, light wins. Shifting between the extremes is horrid.

AKA Both at the same time.

I feel like light mode is way way easier on my eyes, but I generally work in well lit rooms and avoid computers at night.

Plus I think it's important for your circadian rhythm. Bright blue-ish white makes you feel like it's daytime

I find it easier on the eyes if I stare at a screen the whole day.

I don't mind light-on-dark in isolation, but so much stuff doesn't have dark mode, and I find it very difficult to switch.

I agree with you. Plus, as a light mode user I always have hard time when someone is doing code-walkthrough in dark mode.