The online magazine SLATE recently ran an essay "against subtlety." The gist of it is that the idea that a work of art should be subtle is a bit of New-Critical misdirection that has gone mainstream, has become a cliche, and now ought to be retired. Consider Dickens' names! Heavy-handed and wonderful.
My own reaction -- I'm all in favor of subtlety. (And Dickens, names notwithstanding, had a good deal more of it than he is generally given credit for).
Norman Rockwell once created an illustration of Rosie the Riveter on a lunch break. She was seated with one of her feet resting on a book. The book? Hitler's Mein Kampf, of course! This suggests various distracting lines of thought. Did she bring the same book in every day? Did she have to sneak it past security, or was this regarded as normal furniture for a break room? Didn't Il Duce ever write anything she might have used to rest her other foot, or to rest THAT one on alternating days?
Yes, yes, Mr. Rockwell, we get the symbolism. Still...
One might well be overly tired of the subtle/unsubtle tropes discussed in this essay. Yet we should have some vocabulary for indicating when an effort at art has veered into agit-prop terrain.