Here is a Newsflash.
Average women (for a population) is on the overweight size, and clothes are designed to look for for thinner women. That is a fact, I don't deny it, nobody does. They don't design clothes to look good for fat women.
Besides, clothes do look nice on skinner people anyway. Put the same dress (or 100) on a skinny person and a fat one. It is obvious who looks better in it or most of it.