I always saw the Romulans and Klingons more in historical and mythological terms, rather than modern political. Ancient Romans and Vikings, obviously. Hell, when you think of the ultimate Romulan you think of Mark Leonard, who played his character straight out of any Shakespearean depiction of Rome. As for the Klingons, substitute Khales for Oden and Stovokor for Valhalla and they're one and the same. When TOS wanted to be symbolic of current events, they were much less subtle about it. "Fuck it, lets make an episode about Nazis, Commies, nuclear Armageddon, etc."