+1 on this post.
As someone who has worked in colour-calibrated environments since his days (long past now) as a custom photo lab technician, all my backgrounds are usually a mid grey so that what I'm working on is not affected by surrounding values and colours. Too dark a UI and you're likely to make your overall colour scheme too bright because your eyes will compensate. Too bright an evironment and you're likely to go too dark.
It's the same principle as colour temperature. When you're in a room lit up by incandescent lights, the light seems white in colour. If it's night, go outside and your eyes revert to natural light. Look in your window and you'll see the incandescent light now looks yellow-orange by comparison.
It's not a matter of looking cool and stylish. Hell, I don't even like black turtlenecks and horn-rimmed glasses for myself. It compromises the workflow and I'll also chime in about ageing eyes and readability. Not asking the über-black to go away. Just want the option to set the interface colour as I always have.