COD and BF don't have female characters, why was it so important in Brink? My wife is an awesome gamer, when we still played wow, she would always be the best at what she did and people would praise her. She never ever felt the need to tell anyone that she is a girl, she was happy just playing the game as a gamer like everyone else.
Voice chatting is indeed one of those things that you can't really do without getting "busted as a girl" to the guys, but is voice chat really that necessary? I personally never use voice chat except when playing matches with friends.
It was more important in Brink because the game offers the option of customising your character. It isn't based on modern warfare, no front-line army stuff. Plus, COD, MOH and BC are some of the games she's bought and played because they're trusted titles (usually) and there aren't too many obvious competitors. Brink however is fresh, new and from a relatively inexperienced developer so she was never interested in it whatsoever - mainly because she doesn't buy too many games and because she can't afford too many games and would rather trust putting her money into a trusted title.
We find voice-chatting to be a crucial part of our co-op multiplayer experience. Directing each other, talking team-work, networking with other people in other parts of the World etc. It's a joy! We've made a small network of friends just by gaming, people that we then chat to off the console and in person. It's not necessary but when you've got a £60 headset and like the advantages of it, then it's useful.
She just has to mute the idiots, so in COD that's literally muting every single player squealing, singing and shouting down their 'sets. That won't be a problem in Brink because you can only hear your friends (unless you change the settings). But she has certainly felt her brunt of sixism, patronising and prejudice simply through trying to get a few entertaining games on a console - so I can see the stigma attached to female gamers who don't want to be shut out by the minority of fools and the majority of traditional "gamers".
And it's a shame because most female gamers I've played with (easy!) online have been much more mature and friendly than your average guy.
The bottom line for me is that it's unfortunate SD couldn't implement the feature of female character creation and acknowledge why they're not in it. The probability of DLC is very slim but if there's a Brink II then it'll be an option they can't ignore.