::Social conditioning on what constitutes femininity is extremely strong on this one, even though it has no basis in reality.
BG, you are correct...it is conditioning. Now that Brazilian bikini waxing is popular, we are expected to be hair free-everywhere.
However, if it were not for social conditioning, I think we might still be fig leaves. Beauty and what is attractive is in the eye of the beholder. I would venture a guess and say that many European/Asian/WhereEver women shave...their legs, armpits and crotch. I don't think American women are the only ones shaving in the world. Social conditioning pushes how we look. That is a reality today. It is shallow, however true. Again, I don't think Americans started the trend towards what is considered currently attractive....Twiggy comes to mind.
Personally, I don't think a guy needs to shave his chest, legs, arms, butt or torso.
In our society, hairiness seems to be linked to masculinity...at least when it comes to women. If a woman left the house in a skirt & hairy legs, tank top & hairy pits, she would not be looked upon as very attractive by most in society.
My friend has a hairy face. She shaves her face. Personally, it is disconcerting to see a woman with a five o'clock shadow. Now on a man, I think it is attractive....go figure.