How do Katniss's traits hinder her in the Hunger Games?

A very interesting question.  I believe that Katniss's character traits hinder her in The Hunger Games because she is emotionally in the middle of what might actually help her.  On one hand, Katniss is cold and calculating.  A simple example is how she thinks of her family's cat.  She doesn't see it as a family member or comfort companion.  She sees it as another mouth to feed.  That's also how she feels about kids too, and she tells Gale as much in chapter one.  

 "Who would fill those mouths that are always asking for more?"

Further evidence is how she treats the people around her that want to see her succeed in the games.  She fights with Cinna constantly, she sees Peeta as a hindrance, and she generally attempts to distance everybody from her.  

You would think that her cold and hard personality would help her survival chances during the Games, but the problem is that Katniss isn't cold and hard enough.  She lacks, for most of the story, that extreme killer instinct.  She knows that she isn't going to get out of the arena unless she is the final survivor, yet Katniss befriends Rue.  I don't fault Katniss for doing this, but I can't help but think that if she just acted more like Cato, Katniss might improve her chances of survival in the arena.  The way that I see Katniss's weakness is that she is cold and hard, but not cold and hard enough.