I used to be a staunch advocate of light themes, but a combination of extended viewing times, the Samsung G9 monitor (which is both incredibly bright, and almost panoramic, so your eyes are blasted from all angles) and increasing ocular migraines has led me to discover that depending on environmental light levels and equipment involved, dark themes can be a huge mercy. Turning the brightness down isn't enough, as you're dropping contrast / dynamic range. I think something like C# in VS looks prettier in the light theme, for sure, but the practicality and comfort of dark theme let me finally give it up.