Man, I wish I was a chemist -- being a social worker ain't what it's cracked up to be. 8) Seriously, though, I do wish that I was a chemist...
As for why being female would be significant: I've always felt that prevalent social stereotypes shape the way we interpret the MDMA experience. This holds very strongly for sexual stereotypes, since those tend to be the most ingrained and thus invisible. I'm not saying that these stereotypes are "wrong", but they do cause friction when you pop a pill and it suddenly feels ok to touch everyone around you. You have to somehow integrate these feelings, which is when your existing basis for judgment comes into play -- the behavior may be explained away as "drug-induced" or considered "innocent" so that it doesn't beg uncomfortable questions about either your own sexuality or the nature of sexuality in general.
The "innocence" concept is especially interesting, because I do believe that sexuality is an unconsciously menacing or at least annoying factor in some people's lives (male and female). Innocence implies a lack of motives and a lack of appraisal...it's just play, rather than the orchestrated courtship dance we all begrudge.

Whether this is "sexual" again depends on how you usually consider sex. In any case, I think that bringing the MDMA concept of innocent play back into one's sex life can be hugely therapeutic.
*shrug* again, just my two cents, and sort of in the same line as what I've been sawing on about for this entire thread. I've been fascinated by the responses so far and would love to hear more.