I think you are giving yourself too much credit. It's not that the film "requires work", lots of films do. The problem is, there's no payoff for the work involved.
The Lord of the Rings films are 12 hours long with a ton of characters. You can easily miss the fact that Aragorn is some ancient foretold king, so the ghost army doesn't make any sense. Also, it wouldn't make sense why Denethor is angry at Gandalf coming to help him.
The films are enjoyable if you don't pay much attention, because they have a lot of action and cool lines. But they also have an intricate story that improves when you pay attention and watch again.
Cloud Atlas tries to be intricate but the story is just not good. "We are being reincarnated" isn't an original idea. And the execution is tedious.