>> Perhaps a good example is portable (and other) music players: good ones let one quickly go through the content by artist, album, genre, name, etc. as well as custom playlists. Where are they on disk? Doesn't matter.
>Really bad example. I'm still searching for a music player that allows me to select music by filesystem location. Any ("consumer device" as you say) I can find shows you your music by artist or album or genre, and it doesn't pose me a problem (I won't use it though) as long as I can select files and whole directories from a filesystem.
Any player which supports Rockbox (www.rockbox.org) will fulfill the filesystem location requirement.
Personally I prefer tags, but it'd be a strange world if everyone was alike.