XML, and other X[x] standards, are just horrible to read. On top of that, XML was made 10x worse by wrapping things in SOAP and the like over the wire, back in the day.

XSD, XPath, XSLT are all domains where I'd argue that reading/reasoning about are way more important.

When troubleshooting an issue, I don't mind scanning XML for a few data points so I can confirm what values are being communicated, but when I need to figure out how/why a specific value came to be, I don't want the logic spread throughout a giant text file wrapped in attribute value strings, and other non-debuggable "code". I'd rather it just be in a proper programming language.