The fact that this is about the Iraq war will make it age like a fish, too. Sometimes political parody takes some time to get appreciated once there's some distance from the actual events, but I doubt that'll be the case with this movie. I think that the idea of privatizing and merchandizing war, packaging and advertising it, all that sort of thing definitely needs to be addressed in fiction and in real life, and the right movie can bring all those issues to the forefront, but this movie isn't the one. Probably because it's so intent on making that conversation happen.
You can compare that to maybe Django Unchained, which I don't know was trying to have everyone talk about race and violence but was more addressing the lack of these issues being portrayed in westerns of the time or of now. So maybe if War Inc was more focused on being a war movie with those elements rather than a movie about those elements, it would have worked better.