Now, here's your problem with this line of thinking.
None of the armies currently involved in the BF2 universe allows female frontline troops. This is not because they're sexist, but because they pay attention to what other countries do, and learn from it.
Israel has compulsory military service for both boys and girls, but they no longer place the girls in typical frontline units. The reason behind this is actually very pragmatic. It's not to save the women from harm. It's to keep the casualty rates of the men down. They found the casualty rate amongst male personell in a mixed sex platoon would rise, because the soldiers would sacrifice themselves to save the female members. Also, squad commanders were more hesitant to pull back if there was a wounded female left on the battlefield. This compromised squad security and combat efficiency. It's not that the girls are bad soldiers. It's the boys who can't leave their chivalry at home.
Now, several european armies include women in their combat forces, and have good experience with it. They have a different take on things, and can contribute greatly to a squad's efficiency through alternate tactics etc.
Females aren't always girls either. Friend of mine served in Kosovo under a female 2nd lieutenant ("Fenrik"), and she was the hardest platoon commander he's ever seen.
Now, leaving the real world behind, BF2 is, after all, a game, what do you think would happen if female models started appearing? Every single sad geek on the internet would set his preference to "female", so he could lure other sad geeks to stay and support, in the hopes of getting a friendly word and possibly a nude pic over email. I also doubt very many actual females would use the female models, because it would mark them as a huge, inviting target for 13 year old fanboys.
If this could be done without the aforementioned problems, I'm all for it.
Just a word to the guy who's eventually going to model these female characters: Female combat unit members do not have baywatch bodies. The training greatly alters their figure (most of what guys appreciate in the female form is pure fat (tits&ass), and that's the first thing to disappear after months of hard training. Look at decathletes for instance.), and whatever is left of them is covered up by the gear they carry. Additionally, they don't wear makeup. Think more GI Jane, less Tank Girl