On top of that, there is currently only one way to find a file: it’s name.

That is not true, even since the age of basic filesystems, you can already search for files based on type and date.

I know that Windows can search for files which contain search terms as well. Something similar can be achieved on *nix systems by intelligently using grep.

I agree that sometimes, the concept of directories and files wouldn’t suffice. Which is why I’m very thankful of the symlink function available on *nix systems.

However, if you break it down, even the “tagging” concept you’ve examplified in your post. It’s still categorisation.

Perhaps you should also analyse the document tracking behavioural pattern of the user. And once you do, I think you’d probably feel as what I do; The current directory and file structure is the absolute basic anyone will need.

Any other “features” are merely preferences which can be (and usually would have already been) solved via third party tools and/or behavioural change.

The same thing with how computers work at the absolute basic level; the binary system. How can 0s and 1s be enough?

The logic is not to use a system that provides “enough”, but instead a system that provide what’s “necessary”. Anything beyond that is redundancy.