>The problem might, at least partly, be attributed to the absence of a
>documentation element in XSLT 1.0.

On the contrary, I use top-level elements from non-XSLT namespaces for
documentation of top-level XSLT constructs.  I mention this on page 139 of
the 10th edition of our electronic book, and it happens to be quoted in the
Amazon excerpt (sample page 18 of 44) of the paper rendition of the 9th
edition of our book.

I concede there are no documentation constructs to use *inside* a template,
but already being able to add structured comments for templates is useful.