There's a difference between curvy and overweight. The SI swimsuit with the "plus sized model", that's curvy, this dancer is...pleasantly plump?
That said, it's burlesque not ballet, though one could argue there's very little difference depending upon the skit. It's also not pole dancing to Motley Crue while gathering $1 bills from greasy fat guyus sitting on perv row, so the necessity to be thin isn't as great.
I personally would rather see a plump/curvy/bbw chick dancing than some stick figure with silicone. There's nothing sexy about a bag of antlers.