Artists are in a powerful position, they can lead the people by example, and if their message is worth being heard, it will be, and it SHOULD be.
Problem is, most of them don't know jack shit about what they are doing. Susan Sarandon and Ed Asner are prime examples of this. They are using these causes of the week to further their own stagnant careers.
Honestly, what purpose did Penn's trip to Iraq serve? What was he qualified to do? Did he bring home any new revelations?
Chris made better movies anyway.