I to this day think the move from dsssl to xslt was the biggest mistake in the SGML to XML evolution.

they went from a clean scheme based standard to a human-unreadable "use a GUI tool" syntax.

st text serna was a wysiwyg XML FO rendering editor: throw in call stylesheets and some input XML, wysiwyg edit away

but xslt didn't take off nor did derived products.