Most people want to be entertained, not mired into some twisted, complicated plot they'll lose as soon as they go get that popcorn refill. Life already has the complications, so they go to temporarily escape "reality" for a while. Not that good mind teasers aren't good movies, I think that people have way too much drama in their life right now to go pay to see someone else have similar issues.
I think shallow, lighter-weight movies is the trend, now (Deathrace comes to mind). I guess it was so Mustang owners can understand them, too! LOL