While I think the original poster managed to shoot themselves in the foot, they still raise a valid point.
Attempting to rebut this with sexism or outright insults is one of the big reasons I usually avoid gaming related forums. Well done chaps, well done indeed. It's so hard to find good, concrete evidence to support eugenics these days, but you never let me down.
As for the actual issue at hand - I completely understand limiting player character customisation in order to better fit a particular story. This is especially true in context of a game with 120 hours of voice acting. Writing in a female protagonist is going to change too many interpersonal dynamics and require too much of the writers and actors. (It's the same reason why I expect Ashley, Kaiden, and Wrex are going to be largely written out of Mass Effect 2.)
However, the original poster raised a valid point. Our weapon is choice - so long as we choose to have a wang. Michael, not Michelle. I remember when Fable 1 was finally announced for the PC; I told my wife how awesome it was going to be and how we just had to get it because this would be a great roleplaying game where you could really and completely customise your character and play it however you wanted. So long as you wanted to play a dude.
So yeah, I can see why it's necesary from a design point of view (it's Michael Thorton's story; end of the line, no arguements or appeals applicable), but it's not really a choice, now is it?