The only thing stopping you creating a new character to play through with a different build is your refusal to do so as you deem it 'pointless'.
The restrictiveness of the D2 skill system had the effect of actively offering you something new in every playthrough. The openness of the D3 skill system actively encourages you to have only one playthrough with each class. You're right that the only thing stopping people replaying a class is that they deem it pointless, but this would also apply to the vast majority of computer games. What set D2 apart was that you would have to play the game hundreds of times before you could begin to consider repeat playthroughs pointless. I actually like the new skill system as I don't really have the time to play for crazy hours, but it will definitely affect the longevity of D3.
Last edited: