>>95885934
Well there's Mountain Dwarves, Hill Dwarves and Deep Dwarves (Duergar). I'm sure more in other settings other than DnD. In wrestling terms though, Dwarves are the jannetty to Elves. The latter are simply greatly more popular to both male and females (for different reasons) in comparison. It always was and always will be.
Hence the time spent on them.

A better question would be why there's usually only one flavor of Human in a magical world-altering world. Where are the meta-humans?