It doesn't matter that they are larger - it matters that they are different. What bothers me is that there are people who make the claim that men and women have the exact same cognitive abilities, when the only conclusive evidence even remotely related to this one way or another is that there is a measurable physical difference in the male and female brain. Whatever this difference means - whether it be a cognitive advantage for either sex, or whether it has no effect - has not been proven. As a scientist, I don't approve of unfounded conclusions.
There is certainly a great amount of inconclusive evidence, such as the current situation with the gender performance gap in chess. The problem, as well as the main point of this thread, is what should be done about it. Elubas suggests that we do away with titles and tournaments exclusively for women - this is a strong statement in favor of gender equality that relies on the assumption that men and women have the exact same potential in chess. Before that potential is realized (if ever), I fear this would have a detrimental effect in motivating more women to play chess. Then again, complete segregation would make the opposite statement: that men are inherently better at chess than women.
To answer the original question: this ambiguity is the reason why we have separate categories for women. If the ambiguity didn't exist, there'd either be full segregation or no segregation whatsoever.
All arguments considered, this seems to be a no-win situation...
What bothers me here, is this: Why does there have to be a "win" situation? If many women don't make it to 2600-2700, then perhaps they don't deserve a lot of attention if males under that level don't get it (they do I think, but primarily nationally). I say then don't compensate in any way for failing, just deny them that attention. If there are very few women who get there, so be it -- it's not the end of the world. It's sad to fail, but that's life: you only succeed when you do what's necessary. If you do fail, either accept it, or do something about it; but of all things don't complain and ask for exclusive rewards just because of your gender or race!