
I think this was completely about fighting and nothing else. Long hair is a detriment in a fight against something that will use anything to beat you. You will notice that everyone either had short hair or was bald, this prevents long hair from being snatched in a fight thus hindering your ability to battle an agent. On top of that, it could have just as easily have been their own self image, which would be how their hair was constructed.
The argument that long hair is not for fighting does not go along with why many ancient fighters both in Europe and the Orient had long hair unless we are considering the modern military aspect of gun warfare. I believe the women were dressed like modern combatants, with Jada having her medium length hair it what seemed to be anything not to do with the military.