I don't think that women are essentially or "naturally" submissive as a group. Personally, I have mostly submissive fantasies (being kidnapped, being a groupie for a rock band, being exhibited in public...), but there are some people (mostly men) I am attracted to in more of a Domme way, and sometimes I have fantasies about dominating guys.

One other factor is that I think almost everyone (male, female, Dom, Sub or vanilla) has submissive fantasies! Seriously, most of my male friends, even those who are Doms in real life, have admitted to fantasizing about being dominated by a strong, foxy woman. Being submissive, in a "DS lite" kind of way at least, is easier, and it's sort of an instant rush of feeling desired and trusted. Of course most women you've talked to long for that sometimes.

The other thing is that honestly, it's more socially acceptable for a woman to have submissive leanings than dominant ones. Seriously, if you are talking to women in chat rooms or AFF or something and you ask her what she fantasizes about, what is she going to think you want to hear? "I fantasize about being swept off my feet by a dark stranger" or "I fantasize about whipping a guy's ass until he begs for mercy and then making him eat me out"? No one wants to scare away a potential date! And honestly, most of the "acceptable" sexual roles for women portrayed in the media are, to one degree or another, submissive.