There was plenty of moral ambiguity in films in that era, though, if you look at the true classics, the directors just had to be cleverer in how they did it. Look at Double Indemnity, for instance.
Also, modern technology does not necessarily make for a more beautiful film.
I'm not being deliberately argumentative, I'm just saying that I think these reasons for remaking the classics are flimsy. I would much prefer to see the potentially great but imperfect remade rather than trying to improve on films that can't be improved on in any way like The Taking Of Pelham One Two Three or Psycho.