Using a structure other than the file to store information about the file seems like a big problem (like the iTunes example Josh used). It's inherently not port

Using a structure other than the file to store information about the file seems like a big problem (like the iTunes example Josh used). It's inherently not portable. Even if the OS took extra steps to copy the additional data along with the file, that still replies on the target OS to recognize the additional file(s), and incorporate it into whatever search functionality it has. Supporting the tags or metadata in the file simplifies things quite a bit.