Hmmm, well I think there is more to this than it would at first appear.
Generally speaking it takes a whole new framework for a female model, and then a whole new set of texture options to stick onto that model. To do it right is more involved than just sticking a couple of breasts on a male avatar. They could be right, in that adding a female option would have greatly limited the number of options for the male avatars.
I'll also be honest in saying that they might have wanted to avoid the whole "shim" issue. That is to say guys playing with female avatars online. All comments about being "understanding" about it, or how it doesn't bother you, even here on The Escapist there are tons of threads about it from time to time, and I remember hearing some comments about some game developers being a bit disturbed by it from time to time. I've had toons of both genders at various times so it doesn't bother me (obviously) but it's still a big issue.
I'd suspect that given that a game like "Brink" is going to be heavily male dominated irregardless of the Avatar options, they wanted to avoid the whole issue of dudes running around playing girls, and the inevitable "lulz, why do you play a girl?" questions all through it's community.
I remember the subject coming up a long while ago when they first released "City Of Villains" and there were questions about why you didn't have an option for your mastermind minions to be female (even if the main character could be), and so on.
There is no way to know for sure, but I suspect they might just be answering this way to avoid offending part of the player base they might be interested in courting later with a differant game.
