Strong Female role models on tv

Why do strong Female characters in tv/movies/books always seem to have some traumatic experience in their past like rape, child abuse, violent boyfriend, watching their parents get killed, etc. that made them that way? Even My favorite shows have done this, including BSG that is full of powerful (yet, seemingly damaged) Women. Why does there need to be a horrific backstory to explain why they aren't weak, afraid, and curled up in a ball waiting for a man to come in and rescue them? It seems to be obligatory, like it's an apology as to why a Woman would be brave, independent, or a hero (or a weapon, since most of what I watch/read is SciFi). It diminishes a positive Female archetype that isn't portrayed nearly enough. I agree that not all Women are comfortable in that role but are all of the ones that are victims of some terrible past? And besides, if tv is fantasy storytelling why does the fantasy need to include some somber explanation of the girls fucked up childhood that She can never forget.

It's insulting that almost every series with strong Female role models has to tarnish it by suggesting that these Women are only tough, courageous, and able to handle themselves because of some tragedy that has scarred them beyond repair. As if they actually needed to experience that moment of helplessness to become the powerful, capable person that their character represents. Obviously no Woman would just be born that way.

Ironically enough in Japan where Women are considered to be less important then men, their anime series are always chock full of supertough, pushy, determined Women (well, actually 14 yr old girls) who become mech pilots, military leaders, soldiers, unstoppable weapons, etc. because they have the drive, ambition, and natural tendency to want those things, not because they have a troubled past -although Asuka (Eva) had some childhood drama. In fact, it's always the main male character that doesn't have the balls to save the world, complete the mission, pilot the supermech, or kiss the girl.

Maybe if Women had stronger, 'unflawed', role models to identify with there would be less damsel in distress types out there.