In the Cratylus, Plato goes over how well formed language is, and agrees it must have been by purposeful design... and in the end he decides the purposeful designer did such a good job, that he must have been a god.
I think we've talked about this before so my comment here is not a new observation, but this would go a long way toward explaining why Lucretius spends so much time addressing the formation of language - the issue goes right to the heart of whether there are supernatural intelligent forces controlling or guiding human life.