I had not really thought about the change in cover art until reading your article, and yes, you are right. I think the covers that give you a feel of what the story is about is so much better than the proverbial pin-up type of cover. I remember, and have the aforementioned Secret Wars #1 (I think I have two copies with different imprints as I was stationed in Spain at the time, so picked one up from the base book store, and one shipped by my dealer in San Diego). So much can be said about a story with one illustration, and, yes, you are right, a great cover can sell a lot of copies of a comic book.
The modern pin-up type, although beautifully rendered, just doesn't have the same appeal to me, but then I am a Neanderthal who prefers to read comics published pre-1990.
Great article, I really appreciate your sharing your insights on cover art. And yes, not only do I still collect and read comics, I have my daughter into comics as well.