I think you have the wrong idea, I'm pretty sure that women have the option of playing in whatever gender group they want. The division exists simply because there are so few professional chess players that are also women, not because women don't have the mental capacity to compete at high levels. Because there are so few women chess players, their group contains fewer high outliers.
The way I see it, It's actually beneficial for women to have their own section (so long as they aren't forced to play in it) because they are a minority in the game, and the best of the women players should be recognized formally.
Who knows, maybe I'm wrong, and the whole white moves first thing is a racial attack, too (joking, of course).
... I think the information has been with me for some time, but it really just dawned on me now after reading http://www.chess.com/news/world-mind-games-under-way-in-beijing-4917 which contained the line, "The woman's section has ..." unearthed the ridiculous absurdity stewing in me of dividing the competition into same-sex struggles over who has the best spatial relations.
I understand that men typically are more inclined to understand spatial relationships in general. I also understand that in other sports such as basketball or tennis it often becomes warranted as the gap between physical ability based on sex alone becomes a legit issue. Chess is a mental game. Even considering the bias in male brains to entertain larger geometric puzzles, when Chess organizers divide competition to their own gender it's really hard for a rational person to forgive this medieval mindset in today's modern age. I think women's liberation has moved passed segregating gender's in a game that can be played by 9 year-old's, and that when a woman can advance to make money professionally off the legit sport it has become, segregating by sex basically tells me, "You cant play with the big boys and a legit threat to them, so we'll make it easier for you to advance on the basis we need more women players." I dont know, maybe there is some truth in that, but if women want to be treated equal as so many do, then Chess organizations such as "World Mind Games" in Beijing and many in North America by even the most imaginative stretch cannot possibly consider women to be of equal value when it comes to playing this particular mental sport.