If I were a creative director for a game like this, I'd take big issues here. I know people are pointing out the Hollywood blockbuster nature of the single player campaign as a focal point to its incredulity, but it's clear that they still want to have a "realistic" vibe for the multiplayer. Having an entire class be a single sex would be as ridiculous as having an entire class be a single race. And yes, I'm aware games have done that before.Due to the class based nature of Battlefield MP, this is what I assumed they were going to do. For example Chinese Recon class might be female, while the American is male.
In a military shooter with a realistic aesthetic, where everyone is wearing helmets and body armor, there's no need for there to be any difference.