the first one is that all of those people are now dead.

But the main one is how much more real that makes it appear to be. It is like that WW1 documentary that Peter Jackson made a year or so ago "They Shall Not Grow Old" where he took a bunch of historical footage and updated it in this same manner as well as colorized it. It changed the entire way I viewed much of that film. It made it real. Pretty amazing how much it changes our perception of it.