@Fata
I'm willing to bet that if there is a huge, untapped market of female gamers out there, looking for games that focus on female heroes, that eventually it will happen. It happens now. In today's gaming industry, money talks. The cost of producing a AAA title is enormous so the means to recoup their cost is always a concern.
Product branding is a very important part of developing a successful title. Without it, you are hamstrung from the beginning. Mass Effect (each title) has sold over 2 million copies, and that was without promoting a female Shepard. I know there are women out there that love the series, and love to play a female Shepard (I bet there are some that like to play male Shepard as well), but I doubt that the numbers would increase two fold if a female Shepard was part of the original brand. I could be wrong, I have been wrong many times before, but the numbers just don't play out that way. As good as ME is, it's not a 4-5 million unit seller.
Most of those games are multiplayer games.
@GunMoth
Yes, I read your post over in the other thread, but thanks for reposting.
Does Bioware try new things? Of course they do. You have to in order reach new customer bases, which in turn helps maintain and expand your current customer base.
I still don't understand why you think they are more progressive. They started a game franchise staring a male protagonist. They continued the same branding all the way through the series, adding a female image to a CE version of the 3rd and final installment of the game. This took little effort, little money, and they stand to make some extra money from it. If by progressive you mean they made a business decision that will increase their revenue by a small percentage, then ok, they are progressive. I can say without a doubt in my mind, that if it was going to cost them an exuberant amount of money to do, and they figured their return would be minimal, they wouldn't be doing it.
Also, to address your last comment on females that haven't helped the female image...I disagree. Lara Croft is portrayed as a smart, adventurous female that can take care of herself, get the job done, and kick some ass on the way. Does it bother you that they made her look good doing it? (I would argue that Lara didn't look so hot in the very first Tomb Raider game

)
Nariko has the same attributes as any other tough lead character, she just happens to be female. So I am not sure what the problem is.