Thomas, I know why you've asked this question -- it's something I've been thinking about as well. I had the opportunity over the past three years to visit many of the major photo exhibitions in Paris, where I paid particular interest to exactly this aspect of the pictures. I was surprised in many cases to find the photographs I knew so well had less black than I "remembered" from seeing prints in books, and in most cases the lack of really deep black was not missed. Here's a parallel question - is "contrast" just another way of saying deep blacks and bright whites, or can it be something else?