I don't know who the hell printed that whole "thigh gap" thing (I suspect it was Cosmo) but it's pretty much a load of horsesh*t. A very few guys, if any, actually notice or care.
Simple fact of the matter is, most guys like a girl with a nice ass, and most women with nice asses are going to have thicker legs. A thigh gap is much less important than a nice ass, unless you're one of those guys who's into chicks who look like starving Ethiopian boys.
I think that if she's going to have this, she should at least have a nice butt or a nice set of boobs. She PROBABLY won't have long legs so that's a downer but if she's going to have touching thighs, I would hope that she has the other two (one, if not both). Touching thighs just means she works out and is toned and or all of her weight winds up in her thighs for some reason. It can be sexy but..not a preference by me