I can't imagine any other way to interact with data than as individual files in some kind of hierarchy. What is iTunes but a specialized file browser that happens to have a built in music player?
The need for a single, general purpose program for performing actions that are generic for all files just makes sense to me. Say I have a bunch of pictures, a few albums, a movie and an ebook I'd like to share with my mom. Do you really think it would be easier to open four different applications, which probably have four different sets of "sharing" features and four distinct user interfaces? Or to just copy and paste from my hard drive into her thumb drive?
Speaking of which, is this actually a problem? I don't know anybody who has difficulty with the file/folder metaphor. And it isn't like I just hang around technical folks. I know lots of people who could use a "computers for dummies" book.
Which makes me think the real "problem" with file system behavior is that it facilitates file sharing. If people forget they have a disk drive filled with files, and think instead of their "iTunes multimedia blob", then the FBIAA can just lean on MS and Apple to "program out the piracy". Brilliantly evil.