This is an interesting point, especially regarding the second meaning in the following definiton from the OED

Barnyard: adv., towards the barn; barn-yard, (a) the enclosure round a barn, a farm-yard; (b) attrib. of behaviour, language, etc.: characterized by lack of morality or propriety; coarse, indecent, earthy.

Indeed, in this formulation, rhetoric guides us through immoral discourse and helps us identify it.

Maria,

You raise an interesting question here, and the idea you're getting at regarding disenchantment is something I've struggled with this semester, particularly what I'm trying to discern between the good and bad uses of language. I asked in a previous post whether Burke's primary concern with language is good and bad uses of it or whether his concern is expanding our uses of language and being able to track down the implications of what we say. I'm not sure I'm being clear here, but I sense he is more concerned with the latter though he is concerned with good and bad uses and one need only look to his references to Hitler to see this. Anyway, in his move from the Parlor to the Barnyard, I see Burke not necessarily being disenchanted with language per se, but rather is adding to or complexifying (expanding) the process of dialogue, i.e. that it isn't something that occurs only between the bourgeoise in their ivory towers separate from the realities of the real world, but rather occurs amongst the other classes in the sites of everyday life as well (the Barnyard) and is affected by many external considerations such as politics, economics, religion, etc. Also, there is a recognition that dialogue occurs between the Parlor and the Barnyard where all classes participate. So, I see the move as more of expansion than one of disenchantment; however, I'm sure there is an aspect of disenchantment tied up in the idea of the Barnyard, but I'm not sure how to get at that right now, as I'm still working on understanding Burke's concern with good and bad uses of language.