Why do Americans find action movies where good triumphs over evil so appealing?

Western cultures tend to have a bilateral worldview: black and white; good vs, bad, etc. Most Americans aren't entertained by deep thinking; they want their entertainment to be easily digestible. Hence, movies with easy to recognize good vs. bad people. Films reflect this although the past couple of decades have tried to humanize the "bad guys" more (ie: Darth Vader/Anakin Skywalker). Look at how politicians campaign: they try to set the opposing candidate up as a "bad guy" in order to win votes.