Agreed, having worked with a few people who thought xslt is the bee knees it's just not very good at all for this type of thing. In fact I'd say it's not very good at anything really.

My thoughts:

1) It's fragile. As xml is so dynamic small changes in the data can mean your transform doesn't work or worse that it does run but doesn't transform to the correct thing anymore

2) Hard to actually make xslt work. Like there are no decent debugging tools the best you'll get is a site you can plug in data and it will auto run the transformation. The devex here is really really poor which is why I'm baffled anyone would build this. As you say it's a transform language so you can't really step through it you just have to run it and see

3) Very hard to test properly. The amount of times something small would change in the data and then the transforms wouldn't work was awful. The "unit testing" we done was produce a bunch of XML and then run the transforms and check the XML. Like I couldn't actually test parts of the transform as I was going

4) Most importantly was maintenance. XSLT seemed to be a write only language as in hardly anyone as able to pickup someone elses transform and figure it out.

The people who liked it normally only used it for toy applications.