Another aspect of Diablo 3 that's been heavily criticized is the unlimited respecs. Since you can rearrange the skill selection of any character at any time, there's only sense in making one of each class. Unlike Diablo 2, where there were all sorts of variant builds you could make, each one a different alt, in D3 you'd just respec your lone character of a given class at any arbitrary time.
While that's flexible as hell and allows you to more easily experience the different skills without commitment, it also limits the replayability of the game and has a disastrous effect on players' emotional connections to their characters. Not only is your character not unique, in that anyone could duplicate your skill layout at any time by respeccing, not only do you not have specialized alts, but also you haven't bonded with a character using unusual or suboptimal skills to level up. Some say it makes the characters feel too generic.