For an even more positive depiction, try the recent satire film In The Loop. Not only is the plot head-spinningly complex and decidedly highbrow in tone, there is also a scene which shows the young political aides in Washington attending a heavy metal gig. The visiting British diplomat is surprised to see his American counterparts as headbangers in their spare time, but one American commentator explains: "It allows them to unwind. They spend their free time headbanging to metal, and then the next day they go to work and debate noise polution levels in court".
Potentially used for its absurdist context but still - one of the more constructive uses of metal imagery.