I think story is the major reason. For me the most recent example of a film where the audience experience made a really terribly written film enjoyable was BRIDESMAIDS.
No, not know story, I'm not saying that. I think it's more so nothing special? They're sound examples of the typical hero's journey structure, they both excel at the experience. Or, neither are Shawshank.
Which, to me, is a haunting experience, AND an awesome story. I'll re-watch that'n over and over.