During WW I and WW II,I know for a fact,that the president/government asked Hollywood to help them with training films and making films to support the troops/uplift the nation.I can rattle off a bunch of film titles as proof.:-)
Fact is, Hollywood moguls of the time had a much closer understanding of the American people as a whole. Most had actually BEEN poor in their early lives, and had worked their way up. They knew where the money was, and they were, after all, Americans. They knew that those whose husbands, brothers, fathers, friends, etc. who were going off to fight would WANT to see them portrayed as kicking the crap out of the "japs" and "krauts", and doing so in a typically American gallant fashion.
However, times now, and the entire industry, is so different that such a massive show of support would be impossible even if the studio owners wanted to do it.