Most of the programs I use I keep them in dark grey. Perhaps in other programs the gray is better balanced or something. And also perhaps it's better for color correction work.
But in 3ds max I mainly model either individual objects, or building environments. And many times the work is kind of technical and has less to do with composition and lighting.
And the max light ui is not really white. At least the old one. But more of a light gray.
It also depends a lot how do you keep your monitor. I keep it pretty dark because I constantly switch to white webpages, and text documents. With a dark interface I find I have to increase the monitor brightness a lot, making it more annoying when switching to white text documents.
But in the end I think how you got used to it has also a pretty big impact. After so many years getting comfortable to max ui, starting with 3ds max 1, the dark interface just feels unnatural somehow :)
Fortunately the max UI is very adjustable, so I guess I will try some colors balancing in the 2017 dark version.
