I prefer old school, black on white, default & bland theme. It does its job.
Turns out white on black background is not that healthy after all: ux.stackexchange.com/questions/53264/dark-or-whit…
To be very honest, I think 99% of devs out there keep using it because they think its cool. I dont give 2 craps about it, if it makes them happy, good for them.