> Dwarves are good at building things not because of some essential genetic racial qualities, but because they are raised in a culture that values building and passes on a certain set of traditional practices around it.

Really? Let's say that the DM chose to run a game with mermaids in it. Would anyone question the (theoretically) superior swimming ability of mermaids? Let's see how a similar statement reads:

Mermaids are good at swimming not because of some essential genetic racial qualities, but because they are raised in a culture that values swimming and passes on a certain set of traditional practices around it.

It sounds ridiculous, doesn't it?

Edit: And if you're going to deride D&D for that, why not praise it for its lack of sexism (I'm talking about the stats system, not the art here)? The higher amount of testosterone in a man's body makes it much easier for him to gain muscle, but the D&D stat system allows both male and female characters "equal opportunity", so to speak, by not adding or subtracting stats based on gender choice.