Just a small comment on why the desktop environment might need to parse such a file: How about sorting music files according to their real length? Many desktop environments support such a feature, and users like those features, too.
Sure, they're features. Some people like the features. I'm getting old and cranky. My thinking is that I have a program to index and play my music library...I don't need the desktop to know anything about my music, except which program to load when I click a music file. (I've been amazed at how awful this experience still is on Windows...every time you install an application, it'll seemingly try to take over as many file extensions as possible. Microsoft apps, in particular, are egregious about this practice.)
