Having seen two of his plays, I am quite prepared to believe that Steven Dietz may yet turn into a playwright--but having read his fatuous crie-de-coeur for "eloquence," I dread to think what kind of a playwright!
It is a little ludicrous to cry for a return to language when some of the leading writers of the day--Rabe, Mamet, Shepard, Stoppard, Churchill--amply demonstrate the supremacy of language in all their major works.
Or does Dietz believe that cunningly constructed dialogue without explicit thematic declarations is not "using language"? If writers wish "to say what they think about the world" using explicit literary means, let them write editorials rather than plays.
A play is a construct in which image, action and language combine to express theme. To call for a play in which "theme" is explicitly expressed is to call for a drama that thankfully perished 80 to a 100 years ago.