I don't think audiences have gotten dumber, but what has happened for most major motion pictures like Crystal Skull is that the plots have been simplified for a

I don't think audiences have gotten dumber, but what has happened for most major motion pictures like Crystal Skull is that the plots have been simplified for an international audience. When you have to translate a story into 50 different languages, you have to keep the story pretty basic and straight forward or else expend lots of effort in each translation to take into account cultural nuance, humor, innuendo, etc. That's one reason you see so much more reliance on special effects and crazy action. Because those are pretty universally entertaining. So in other words, globalization has ruined the film industry.