To be fair, IE3 and, more specifically, Microsoft News and Mail, had one intriguing idea - that mail (and NNTP) messages were things to be managed like files and folders by a shell extension.
I would love to have Nautilus turn into a mail or calendar client when opening specific folders (somewhat extending magic into discovering what a folder is about)
I’m quite happy that the world has been moving into another direction. You no longer have to browse your music or photos in the filesystem, you have a dedicated music or photos program. That seems ideal to me, I wouldn’t want my file browser to be a swiss army knife.
There's no need for it to be a completely separated interface, though - in theory, at the top level you could have "Files", "Music", "Photos", "Mail" and so on. When you descend into "Files", you see the root of a traditional filesystem, when you descend into "Music" you see a music-specific interface.
It's really more of a question of "Why does my shell currently privilege file browsing above music or email browsing?" I would contend that it's for historical reasons more than anything else.
But that's the point of what I was saying - when you are browsing your music, your filesystem browser becomes a music program. If you want to see files, switch back to files view and you are done.
I am not saying this is how every file browsing should happen and how every program should behave, but, for some data types - like mail, videos, music - it makes a lot of sense
I would love to have Nautilus turn into a mail or calendar client when opening specific folders (somewhat extending magic into discovering what a folder is about)