This is a good point. We never thought of these strings as URLs, but there are places where it would be nice to use them that only want URLs (the href attribute, for example).
The way we have it now is nice in that any valid URL can be used to locate a database. I am loathe to restrict that.
The hash portion of a URL is not transmitted to the server by browsers, so it wouldn't help in the case of putting the string into a URL bar or a hyperlink.
If the resource you're linking to is a database (or to speak more strictly, if its only representation is a resource of a noms-database media-type), rather than an HTML page or something, can't the browser can be configured to pass it off to a Noms implementation, complete with the dataset identifier within? I mean, that's what people do with page numbers in PDF files, right?
The way we have it now is nice in that any valid URL can be used to locate a database. I am loathe to restrict that.
Interesting point though - thank you!