I'd say XPath a way to get a nodeset or another XPath type out of something. E.g. the current date is not selected from a document. There always will be a need to get yet another thing as a nodeset, e.g. list a directory. Or, for boolean expressions, there will always be a need to test yet another thing, such as an environment variable.
These things, of course, should come as extension functions rather than special syntax, but then there will be a need to provide a small standard library of such functions :)
So yes, I believe it's useful if we're going to use XPath in a trusted environment, e.g. as a typical command-line tool. You won't deny Bash or Python this and other powerful abilities, will you? But of course it would be very unwise to run an untrusted Bash script.
These things, of course, should come as extension functions rather than special syntax, but then there will be a need to provide a small standard library of such functions :)
So yes, I believe it's useful if we're going to use XPath in a trusted environment, e.g. as a typical command-line tool. You won't deny Bash or Python this and other powerful abilities, will you? But of course it would be very unwise to run an untrusted Bash script.