If you're within 10-15% or so of white or black, I am fine with the "slightly grey" look, assuming I don't have an AMOLED screen, where your dark grey is just wasting my phone battery.

I really only get annoyed with the "less contrast" meme when it's something like a Google website where the UI disappears if your monitor's contrast settings weren't tuned professionally. (I used to have to adjust my monitor settings around making the UI elements on Google+ visible.)