the big probelm was how kathrine played her

She did....multiple times. She broke down when her landlord calls her and says they have to move out because he wasn't able to pay the rent, she broke down after her first "surgery" job at the club, she broke down (in disgust, which still counts in my book) after her first "real" operation on Ruby RealGirl, she broke down (throwing *beep* off a table and flipping it also counts in my book) after her rape, she broke down when she caught the blonde chick sucking Billy off. I'm sorry, but she broke down more times than your average MTV teen brat (and this is a good thing, given the subject matter and what kind of film it is).

She DID break down, insensitive and emotionally stunted OP!

The other characters care about her, and we care about her journey because we saw where she started and where she ended up.

We saw her hope and promise in the beginning, destroyed by the very system that is supposed to nurture and protect her and allow her to develop and contribute to society.

We saw her enthusiasm and her skill in the beginning, and we saw it exploited by both the criminal underworld as well as the supposedly legitimate official bureaucracy.

We saw her hope and dream for success and a normal life and we saw how it went wrong.

We saw her try to do what everyone is told they are supposed to do - go to school, do well, get a profession... and how it derailed.

We saw ourselves and the people we know in her, and we saw her fall from grace, and we cried for her and for ourselves and for all of the human race who find themselves in such circumstances.

When we see her blank face and her descent into madness we are shocked and saddened and weep for her and her loss. For the loss of our species, the difference between what positive things we could be and what we actually are...