Making new characters was cast off as "boring", in favor of a system where you should never switch characters. Where you are supposed to play through the "content" for 1000 hours repeatedly.
I dont think the developers realize that the real content of RPGs is creating characters that play the game completely differently. Otherwise it just gets old. You replay the game because you can experience it in a different way than you did before.
If you make more than 5 characters in Diablo 3, you are doing it wrong. If you don't spend the high majority of your time on your main character in Diablo 3, you are doing it wrong. And that is the problem, in my opinion.