Having a single template is not weird, in fact while XSLT was being
designed it was thought to be such a common and important use case that
a special "easy" syntax was designed for that case. The "literal result
element as stylesheet" (or in xslt2 terminoligy "simplified stylesheet")
If your stylesheet just consists of a single template matching "/" you
can drop the outer xsl:tstylesheet and xsl:template element markup.

Hmm, I have read through the recommendation a dozen times, but it seems that I
have always missed this section. Now things become clear... :)