I think it's just an individual thing, and we should all respect that. There is a litany of posts and opinions of people who say their eyes hurt with a light color scheme, or it produces spots in their vision, or it hurts their concentration etc. I have no reason not to believe them. Many people prefer to even show their code in a dark scheme on websites. Furthermore, many people don't care but think dark is cooler.…
It's not that these people are lying, but it is common that people's subjective experience is biased by their expectation.
If I expect that dark themes are easier on the eye, I'm likely to experience any eye strain that might be caused by a bright theme in an exaggerated fashion.
Similarly, if I were to buy into this "the Pulfrich effect will slow you down" hypothesis, I might subjectively experience a benefit from switching to a light theme.
I don't buy into the hypothesis, so I'm sticking with a dark theme (as well as f.lux cranked up to eleven).