Art imitates life
There's a reason why most of the soldiers in modern FPSs are male; because most of the soldiers in real life are male. As are the overwhelming majority of combatants in every conflict since before recorded history.
Heck, if someone somewhere is doing something dangerous and exciting, they're probably male.
Now if every society on Earth has shared this trait, then I think it's fair to say it has some biological component. Successful societies have thrived just because women weren't willing to dive on enemy swords like men are (which is kinda obvious, a dude can father hundreds of children a year, a woman can mother maybe 1. If survival is an issue, we need more women than men).
Maybe at some point we can overcome this with society, once women start taking dangerous jobs and having adventures like some of our menfolk do, so then the idea of a female protagonist in a dangerous game might seem more reasonable to the gut instincts of the unwashed majority of gamers. Possibly. Eventually. But I'm not holding my breath.
Making women is HARD WORK
Stop making it a no-win for games designers. Female characters face ENORMOUS amounts of scrutiny for every single aspect of their design, compared to their male counterparts. Too much/little sexuality/femininity/violence/sexiness/dialogue/vulnerability/characterisation/etc. It's tedious. It's unfair.
If it wasn't such a minefield of offence, then maybe that'd mean more people would try.
Coercion is almost as bad as censorship
Complaining that you want more female characters in a game is totally fine. You're just saying what you want, after all.
However, saying that there's a moral obligation, and that we're somehow not good people if we don't have gender parity in our games, is not cool.
Games are already awesome for women
Saving anyone from a badguy's castle, princesses included, is actually a nice thing to do, so let's not demonise it unnecessarily.
And if you ever think that the gaming industry isn't doing enough to promote an image of strong capable women, just consider that with the invention of Lara Croft alone, there's been about a 1000% more tomb raiding women in games compared to female tomb raiders in real life. Ditto that (to a greater or lesser degree) for any other typical gaming profession (professional fighter, bounty hunter, soldier, etc). Games are already leading the charge on presenting the genders more equally, our so-called egalitarian society is far far behind.