This is a great thread, BTW.
I think one thing that has to be brought up here is historical (and personal) context. When I was younger I was more easily impressed with loud flashy movies with lots of special effects. I was not at all interested in watching "old-fashioned" black and white movies. However, this opinion was pretty much a result of ignorance--it wasn't based on much real experience of those movies. Over the years I started watching older and more obscure (and foreign) movies, and talking with people who loved these movies, and eventually my tastes grew outside of the box.
Yes, a movie should be able to stand on its own without explanations or excuses. However, show a young kid a movie like "Transformers" and then show them "The Great Train Robbery" from 1903 and try convincing them that The Great Train Robbery is the far superior film (good luck with that).
The other issue we have here is where you were in your life (and how old) when you fell in love with the movie (or music for that matter). I think many people start discovering their tastes in their teens, then they hit a "golden era" for a while where they are discovering all these great things, then their tastes start becoming more refined and nuanced as shock value and novelty starts to mean less and less.
"I'LL SHOW YOU THE LIFE OF THE MIND!!!" - Barton Fink