At the beginning of Coraline, our heroine is bored at home: her parents are too busy for her, the place she lives is dull, and she has exhausted all the exploring there is to do. It takes being in a crazy and super scary alternate world to make Coraline realize just how much she appreciates her real home. The real world might be dull sometimes, but it's home for Coraline. This is a common trope (common device) in literature and film. "There's no place like home..." – ring a bell?
Sometimes home is really about what's familiar; even though Coraline might like her room in the other world better, it's just not home.
All it takes to be at home is the right company. Coraline learns this lesson the hard way.