Well, maybe they had a good reason - at least insofar as Terry Jones can tell:
What's interesting about this is pretty straightforward. In a quick half-hour show, Terry provides a glimpse of medieval life for peasants and that's pretty useful for the aspiring RPG referee. Past that, some of what Terry talks about gets even more interesting if you start to mix in magic and its place in a D&D society. Unfortunately, not many campaigns actually explore or reflect how magic is itself a kind of technology.
If you think about it, a D&D world might have some pretty sophisticated approaches to health care, farming, town planning - you name it. Some of this analysis was done in early issues of The Wild Hunt - unfortunately, I don't think I own most of those. Something to dig up out of the past!