I like to think that males are generally driven by testosterone for the most part in games... this is this sudden recklessness that makes the hero make mistakes, if a female character was to be the main hero (and wouldn't be some uber super giga chick but just someone regular) chances are she might just think it through and solve the problem at first (which results in no game at all) or simply stop to bother about it... lol... ok sorry, I do realize this was a stereotypical comment, do not worry.
Trully though, I think Leric has a point. Writers write characters from their fantasies. Obviously, one could write about how handsome a man is, but they could also write about their cunning (Ulysse) their strength (Hercules) their courage (David) etc etc etc... but for some reason, the only (or strongest) fantasy men have ever felt for women was pure lust or feelings of the same kind. Therefore, its easy to make a thousand different men in a game with different attributes that you look at, but it is much harder to give women something else than looks OR MEN's derived qualities (in case you didn't notice, Lara Croft is probably just about a man transposed into a woman, there wasn't much work involved, she's basically G.I. Jane with big tits).
I won't generalize here, but a part of women can be softer 'creatures' and can appeal to emotions and whatnot (sissy characters who don't seem to fit in the game so obviously we need to link them up to the hero, and since we can't make them important by what they bring to the hero, let's just make them fall for him... wow... this is basically saying that the girl is pointless and can't live her own life for herself).
It is a good thing you note that fact though, because in some games, it just went way too far, as if its a universal fact that we need to accept... Best example on top of my head? Dark Messiah. First time you get to see the villainous girl, she's already a whore... how about the 'good' girl? she's in love within the first hour, and at the first skirmish she moans like a lil bitch whose affraid her sugardaddy will perish, I mean cmon!. I'm sure I'm not the only one whose girlfriend has the nerves to temper down once in a while with a cold 'stfu'. They are just looking for the perfect slut or the perfect softhearted chick whose patience is more than a single woman could ever handle without turning insane.
EDIT:
ROFL LMAO OMFG nice video ;)