In my (brief) experience with YAML, it seemed like there were several different ways of doing things, and I saw this as one of it's failures (since we're all comparing it to XML). However I maintain, in spite of all of that, that it can easily boil down to the fact that, for someone who knows the most minuscule amount of HTML (a very easy thing to do, not to mention most people have a tiny bit of experience to boot), the transition to XML is painless. YAML, however, is a brand new format with brand new semantics.
That's true and a very good point. Like you said, that's probably the reason XML took off, because of our familiarity with HTML.
As for the human read-and-write-ability, I don't know about you, but I
have no trouble whatsoever reading and writing XML.
You might like programming in XML then: http://www.meta-language.net/ :) -- http://mail.python.org/mailman/listinfo/python-list