I've done a little more research. The German phrase Carlos Piera cites translates to "The Law of Lengthening Limbs." This is the tendency to order list-items in ascending order by syllable length:
and the American way
Roman Jakobson mentions this briefly in "Closing Statement: Linguistics and Poetics." He says that you are more likely to say "Joan and Margery" and "Margery and Joan," associating this tendency with the "poetic function" of language. He doesn't say why, just that it sounds better. Piera is another one, citing the German guy who coined the phrase, so there are at least four or five people who have noticed this, including me.
It is probably weaker than a law. It is more of a tendency. Let's say it will happen more often than not, in the weakest formulation. The implications are not profound, maybe, but I find this kind of thing fascinating. As far as I know, there has been little discussion of word length in linguistic or literary prosody.
The nuclear stress rule (Chomsky and Halle) says that you stress the right-most stressable element in a phrase. We know that important elements tend to go last, and that ascending order is preferred in the rhetorical figure of gradation. Curiously, most dictionary definitions don't talk about word-length in relation to figures like "climax" or "gradation."