Coraline's journey makes her realize the importance of home.
Coraline recognizes that "home" has limitations. Coraline's mother shows love for her, but has no time for her. While her father is good to her, the food he makes is not to her liking. A combination of curiosity and restlessness compels Coraline to unlock the door into the world of Other Mother and Other Father. Coraline finds herself entranced by Other Mother's love for her and Other Father's sense of humor. As the toys come alive, Coraline revels in how this setting contains everything that her real world lacks.
Over time, Coraline realizes the dangers beneath this alluring vision. She understands Other Mother's desire for control. Like so much of this world, she recognizes that Other Father is merely a part of Other Mother's plan. Coraline realizes she will be trapped if she stays. As a result, she recognizes the need to get back home.
Coraline understands that a flawed home is better than the world of Other Mother. Imperfection is better than imprisonment. Having buttons sewn on her eyes and becoming another member of the mournful parade of ghost children is no way to live. Coraline's aching to go back home helps her redefine it. She understands its real value. Ultimately, while it might not be perfect, home is where Coraline can be free.