There’s a few good use-cases for serialization; for me the first and foremost is the performance combined with ease of use.
In AIR we have SQLite access, or in a bad case we can write some format to a file and recover it later somehow via parsing. But why? That’s a lot of work… And it’s not the fastest approach either.
And what about if we’re doing a browser application that we want to save a state of something, but don’t want to host the storage and write a web service to handle data?
We don’t have stealth access to the filesystem directly, which makes it hard (errr, impossible) to silently store things on behalf of the user.
We can actually tackle both easily using serialization.