She was a flawed human being: she had a caffeine addiction, she was stubborn, she had some obsessive tendencies when certain instances occurred, and over the course of the seven years we saw hints of a self-destructive streak. She coped by making "getting the crew home" her anchor, the thing that drove her on - her primary obsession, so to speak. It became more important to her than her own life, as shown.
For all that, she's a far more interesting character than is superficially shown. She's almost pretending to be a perfect Starfleet Captain even though she isn't, and even though she's almost emotionally crippled by self-imposed expectations. It's a more nuanced performance, more nuanced writing, than I think even it is trying to be. And that's why I love the character.