As currently configured, an XML document can be rendered via CSS or XSLT within most modern browsers as XHTML, HTML, SVG or other established formats (unless that's changed recently). JSON does not support that capability right now. Kurt Cagle Community/Managing Editor Data Science Central, A TechTarget Property
I'm afraid I don't quite see how that's relevant to the thread, which wasn't asking about practical utility, it was asking about expressive power.
Michael Kay Saxonica |