Is it time to get really perverted and specific over sexy anatomical traits? For me there is something about that 'gap' between the thighs that drives me nuts. A girl can have an amazing curvy figure but if the thighs are touching each other with no gap in between it kills the magic.
I guess it is something hardwired to do with child birthing capacity...
I think it enhances the appearance of wideness to the hips, which is a well recognized secondary sexuial characteristic and signal of female fertility and, ergo, attraction but without the fatness (which then closes said gap) that comes with age and decreased fertility.
Buttock implants and other cosmetic surgery is extremely common in Brazil. So they are unlikely to be totally natural. Still a zillion times more beautiful than the plastic fantastic north american style of cosmetic surgery, which is usually some horribly skinny woman with oversized fake boobs, with creases around them from the stretch.