Dwarves have massive asses, they just don't usually wear the kind of clothes that accentuate it (also, they're kind of hard to see for tall races)! I mean seriously, they're supposed to be stout and have a lot of stamina for working in mines and the like, you can't really have that kind of build with a flat ass.
Small, yes, but Konsi is pretty far from horrible.
Also I've never seen her eat a beetle, but you'd know better than me on that point.