well that's because the game is popular. It's the hype, not the swords, spells and dragons.
Strange; me, my girlfriend, and my girlfriend's mother all play it for the swords, spells and dragons.

Her mother is a huge fantasy geek, and milady got into TES because I was so keyed up about it. And I wasn't keyed up because of the hype; I was excited because I've played TES since Morrowind, and after the Bloodmoon expansion, I couldn't wait for a TES set in Skyrim.
Based on my personal experience, I have to agree with the poster who said that the gender gap isn't as pronounced as it used to be, and that men and women aren't as disparate in their interests as people tend to assume (spend 3 days where I live meeting all the redneck chicks.
They are everywhere). *shrugs* I'm a nerd, and a gamer who started with Sonic the Hedgehog. It doesn't mean I have [censored]-envy; it just means I like gaming and things traditionally labeled nerd-interests. Sort of like my 'mother-in-law' is in her 50's, and she's getting SWTOR soon: it's not just 15-30 year old guys "with no life" (whatever that means) playing games and watching the Syfy channel. It's an unfair stereotype for
eveyone who likes those things, and I'm glad to see it falling by the wayside.
I'm not much for going to a forum and announcing my gender, because I don't really think it matters. It's not that remarkable, really, and it's on my profile if people care. There are some forums I've been to where I'm still referred to as a guy, and I (personally) don't care enough to correct it, much less be offended.
And on the subject of role-playing the opposite gender: It's role-playing. I play as a guy about half the time (especially on RuneScape, where I got tired of being hit on by 13 year old boys XD), because when I sit down to play a game, I'm not playing an avatar who is the same as myself. I'm playing a character in a world, who has different opinions and approaches to life than I do. Some are male, some are female. A guy playing a female character isn't suffering from some sort of 'deviance' (creepy advlts luring teenagers notwithstanding), he's just playing a character in a fictional world.
Anyhow, to the OP: I didn't get the impression that you were trying to be a jerk; just that you were pleasantly surprised. I'm not trying to nerd-rage on anyone, just giving my anecdotal 2 bits.