XML was a great idea. At some point in the early naughts, however, XML-abuse became rampant-- too many crappy tools, too many half-assed attempts at putting square pegs into round holes. It didn't help that XML got inextricably associated with those horrible over-complicated ws-* standards that ended up sending Russian novel-sized "hello world" information exchanges.

The main idea, however, was wonderful. An information exchange format (xml itself), a way to define schemas (xsd), a transformation language (xslt), and stylesheets (xsl?). I kind of miss it.