A female's skeleton, especialy that of a girl, does not greatly affect the way in which they move (unless they're pregnant, but then why the f*** would you be doing parkour?). I have been doing long-distance running for four years now, and still many of my friends who I run with are female. Often when I'm conscentrating while running my vision blurs into the distance and, on more than one occassion, a have mistaken males that I do not know (I can recognize the movement of people that i know) for females and vice-versa (fact: the greater the distance in running, the less gender matters. Some ultra-marathons [i.e. 200-miles] have equal average performance by women as by men).
It's funny that you back up your argument with long distance running instead of actual parkour.
I do parkour and I have seen woman drop down and land a wall hang the same as a guy but then their boobs cause them pain, so woman usually land wall hangs differently. So Instead of trying to justify how woman and men move the same, just remember that they usually don't.
But when you get right down to it, SD has explained many times that they regretted not being able to implement female characters as it would reduce the quality of customization dramatically etc.. Also alot of the other reasons on this thread are very vaild (I.e Shadowcat)
But IMO when Brink does well, there may very well be a female character DLC but the amount of balancing that will have to go into getting Female characters to not have an advantage over males (Due too less target area I.e Slimmer) may be too hard, not to mention the DLC will more than likely have to be free so that everyone can see female characters.
But hopefully it could be possible.