I'm just popcorning over people being all "A characters sex shouldn't be a big deal" then making a big deal out it. From what I understand there is no reason The Doctor couldn't have rebirthed or whatever as female so it makes sense since the coin flip landing on male 12 times in a row is pushing the odds.
Geekdom is by an large a good ol' boys' club. Not "No Girls Allowed," maybe, but certainly "girls allowed only when playing by our established rules." There's a lot of residual bitterness, I think, in the geek community right now among "adult" geeks (say, 25-40) who grew up in an era where it was predominantly white suburbanite boys who, if you were into things like comics, D&D, video games, sci fi, etc. meant you weren't getting by your dream girl, ever.
Now these girls who (they assume) wouldn't have ever been okay with their interests before (and certainly wouldn't have been sleeping with them) and they've carried this sort of insular mindset into a now-wide-open world of possibilities and it's revealing many of them as really no better than the "more popular" subcultures that they felt wronged by in years past.
TL;DR it's like everything else in this country. "Getting there, but not there yet, and some people are going to try like hell to keep it 'the way it was.'"
TL;DR for the TL;DR: it's about sex.