Ditto for users. And same for URLs. I'm not so sure they are. True, existing applications use URLs like filenames, but then again, that's all we have. When I send mail with MS Exchange, I use the recipient name and not an X.400 address, but if there were no directory facility I would have to use X.400 addresses.
Directories are at another level, one more indirection.
Here, I have mixed feelings. I think URLs should be readable and easily remembered. And, of course, URLs are embedded in hypertext, so even if a directory service is used to provide appropriate human understandable reource names, the links in the document will still use URLs, and so we are caught in a bind. If you're going to reinvent the wheel, at least try to come up with a better one.