XML vs Serialization
In this XML vs Serialization post, the author lists reasons why XML is not a good serialization format. I would turn the list around and say those are the exact reasons why XML is a good way to develop a serialization format. Even if its just an XML dump of your object model (I think we could do better than that), it's still better than a binary dump. If my object model changes, and it surely will, I can always transform the older XML dump to the newer structure. Even if its by a hand-written script. You can't easily do that with binary.
Also, I don't believe serialization implies the object model is more important than the data. I prefer to think it means the object model holds the data.