It's a long time ago that I played WBC2, but in two they are incredibly slow to start, their basic units aren't even good, everything is expensive as shit and their economy needs a long time to get going, and their hero skills are lacking good synergies or skills to offset their disadvantages. And no, rune magic is not a good sphere. Whenver I play dwarves, it's with some other races hero, especially economic heroes.
Why dwarves never got the Smelting skill is beyond me. No race has that.