although i am unable to provide an adequate explanation as to why, i can confirm that your premise is absolutely correct - i love girls in yoga pants. and guys in tight sweat pants do nothing for me either :2 cents:
Some men just like seeing the shape of a women. A nice woman's physique is just more pleasing than a man’s could be. It's inherently beautiful. With a man, even the ones in shape, not so much. :dunno: