To Mayo's point, hairless-ness is not a specificly feminine trait. While women are far less hirsute then men, the shaving is to present as younger. The concept of being younger = more attractive = closer to better reproductive age is very important to many of the espoused ideals of beauty in our culture. Right or wrong. Make up? Health and youth. Gravity defying voluptuous figure, health youth and baby bearing. Long, shiny nice colored hair? The same again. And of course our society, and especially marketing, tends to over value, and thereby stylize, sometimes to the degree of characterized presentation.
Oh crud. Now I'm a feminist?