I think the main problem was the hosiery, not the clothes - you can see the elastic waistbands of the tights (pantyhose) digging in, even on most of the skinny models and that's what made it look all lumpy.
Also, the shoes are too high, of course.
Unless you have big feet, the angle is simply too great to walk in them properly and most curvier girls (even tall ones) tend to have smaller feet in proportion to their height than skinnier girls; it's just a body type thing, I think?
Also, I've noticed that curvier girls tend to have higher arches, too - which, again, increases the angle of the foot in a heeled shoe.