In my case, I needed to put together table headings that were clickable that would sort the dataset. XSLT can do that, but midway through doing the task, I realized that I was working with stuff that belonged in a database, accessible from more places via SQLite. Since I needed a multitude of different ways to sort and filter the data set, I made use of VIEWs to abstract the filtering and turned it into a CLI tool.

There's still an appreciation in me for XML (specifically SVG), so maybe I'll try something else with the tech. Care to share a link or example to more of what you're talking about?