I like this a lot. As a personal example, I was recently reading about the debate over allowing women to be in combat jobs in the US military, and trying to decide where I stood. Egalitarianism is good, definitely, and they've proved themselves capable as de facto combat troops in Iraq and Afghanistan. But can they meet the physical standards? What about unit cohesion? Ahhh!

Think about it this way: Why are sports segregated by gender once one gets to a high enough level that people care who wins? What would happen if both genders competed in the same competition?

Well, the top level would still be dominated by one gender, mostly male with the possible exception of things like gymnastics. Also in violent sports like (American) football you'd create awkward situations due to the fact that our culture still has a strong taboo against male on female violence. Now apply the same logic to combat.