Face it, the vast majority of sci-fi and fantasy fare - and I mean books, movies, videogames, comics, and so forth - are written by and for men and boys.
When it seems like nobody is paying attention to you, the slightest bit of attention paid by anyone can seem like a huge deal - come to think of it, it's often one of the first things (however unconsciously) noted by real-life "Bella Swans" right before they wind up in abusive, co-dependent relationships with the first real-life "Edward Cullen" who shows something resembling interest.
Now, am I saying that all this context somehow justifies or minimizes the blight of "Twilight?" Hell, no! In a way, I think it makes it worse. Bad art is just bad art, but what Stephanie Meyer (and her publisher, and Summit) are doing amounts to selling tainted water to an audience that's dying of thirst in the desert. Plus, they're driving down the value of the genre even further by occupying it. Anyone trying to pitch a good female-centric supernatural romance franchise will inevitably have their work compared to "Twilight" and taken less seriously as a result.
So while it's all good and fun to bag on Meyer's crappy books and their goofier fangirls, just keep in mind how hard it is out there for the women of geekdom. Their own culture relegates them to the subgenre-ghetto, and the "Twilights" of the world grow fat and wealthy keeping them there.