Quote from ThumTrick
Sorry, let me rephrase - I think this would add meaning where meaning is lacking. In D2 there were multiple reasons to level new characters. In D3, no matter how you slice it, there aren't. You might level a new character so that you can keep a different build ready to go, or you want to have both a male and female character, but that's about it. And there's nothing wrong with the way it is. This would just give one more reason to reroll and could be considered an advanced crafting mechanic.
What exactly were the multiple reasons to level new characters in D2 that are lacking in D3? I can really only think of two: 1) You screwed up your build, although this was eventually removed as a reason to reroll with the respecs, and 2) You play on ladder, and the ladder was just reset. Well, I don't know if you realize this, but the majority of D2 players did not play on ladder, and if they did, they switched over to non-ladder once the ladder was reset so they could keep playing with the characters they had already leveled. I suspect that most of the people knowledgeable enough about the game to be posting here played on ladder, and leveled new characters after each reset (which, by the way, didn't happen until several YEARS after the game was launched), but places like this forum are not exactly representative of the entire playerbase.