Some interesting suggestions I have gotten have been:
Part of the problem is that stars don't seem to be seem to be rewarded for being elegant/classy any more, so why should we expect them to be? Also, the press tends to be harder on entertainers in the 21st century and is better at finding out dirty little secrets.
This list so far seems unsatisfying. Perhaps I'm expecting way too much? What do you think? Do you have any names to add?