Unfortunately this kind of gendering is rife, and not just in gaming. And companies tend to eat it up, and push parents to do the same thing. When I was little, there were games marketed to both genders. Lincoln logs. Legos. Now Lincoln Logs and Legos are boy toys only, except for the girl Legos (I forget what they are called) that are, apparently, already partly made and such. But part of that is because Legos come as kits, now, rather than bricks you can make whatever you like with.
Pink games for girls have been around since the early days of gaming, but now gaming stores etc. are just rife with them. And, you don't really see any "older" games for girls, i.e. Teen-rated games for teen girls or M rated games for adult women, unless those games are gender neutral. Then there are parents who are horrified their children will turn out to be gay/lesbian if they're into the "wrong" gender of stuff. I think they need to worry less about that and more about the content of the game, and what it's telling their children.
I know someone who worries horribly about his son being gay because he likes My Little Pony stuff and plays with his big sister's games from time to time. But the kid also loves trucks and cars and racing and engines and typical boy stuff. He likes My Little Pony probably for the same reason most of the teen-to-adult bronies do: apparently it's actually a really good cartoon (I haven't watched it, so I don't know). As for playing with his sister's spa games... well, admit it, it's pretty hilarious to stick cucumbers over someone's eyes and paint their face with green mud. And it's even funnier to a young child.
Something that I meant to comment on before, but it was late, or something... Regarding the low number of female characters actually played to completion in Mass Effect. Women are more likely to play male characters than female, and more likely to be okay with playing men than men are to be called upon to play as a female. The same is true for novels. A woman is more willing to read novels with male protagonists, whereas men often think novels with female protagonists are too girly (same person as above was also afraid boy-child might become gay because he read books about girls--I say they should be happy that the child enjoys reading a good story regardless who it's about--no one thinks a girl is going to be a lesbian for reading a story about boys).
Basically, the way I've seen this explained--and I tend to agree--women are trained from birth to empathize with men, to be able to put ourselves in their shoes. We are inundated from childhood with male animal cartoon characters, male heroes in our cartoons, male protagonists in our novels, TV shows with boys and men as the stars. The characters we are expected to understand and enjoy are predominantly male, even today, even in 2014. Most children's book characters are male, even the nonhuman ones--girls are expected to read about boys as much as about girls, whereas boys are generally expected to only read about boys, even if the boy in question is a puppy or a giraffe. Most men are, on the other hand, taught from their boyhood days that they must never be at all feminine, and to avoid anything girly--no watching cartoons with female characters, no reading books with female characters, because those are for girls only (even if the entire plot or premise of that media is gender-neutral). Putting themselves into a woman's shoes would classify as overly feminine, unless they claim to do so for the sake of sex appeal. And women are also generally told we should expect a man to protect us/take care of us, so many women do gravitate toward male heroes, because they have never been taught that they can/should be their own heroes. That's the society we live in. it's not true for absolutely everyone's upbringing, but I'd argue that everyone who hasn't been living as a hermit has been exposed to at least a little bit of it, through school, daycare, babysitters, etc.
So basically, a lot of women will still play the male protagonist, if he's the default, and some will play the male option even if the female character is given equal presentation. (This is particularly true for ME2 and ME3, when women playing the game were likely to not only be starting a game with a default male, but also might be loading from a save where their character was male in the game before.) That doesn't mean that they aren't playing, and it doesn't mean that the female character should not be marketed. A lot of women like the idea of being their own heroes, and showing them that the game isn't just about another man character, but that they can make their own unique woman character, would go a long way to appealing to a broader female audience. It may also encourage some of those women who otherwise would feel like the male is the "real" or "right" version to actually play the female character, making the balance a bit less skewed toward male overall in which character is actually played.
But what do I know...?