Sometimes they are... but more often then not a movie is mistaken as propoganda when it is just appealing to its market. When filming a war movie Americans generally want to see Americans win. I don't want to watch a movie about My Lai. I want to watch a movie where there are challenges that we face, overcome and win. I don't watch Saving Private Ryan to watch some Germans win and get Ryan.
Also, movies are changing. People want more truth and accuracy in their movies than ever before. I think that a lot of this started with the classic, The Outlaw Josey Wales. The Natives were not bad guys. Whites were bad guys and good guys. It was confusing. It was real.
I agree up to a point, but you miss the fact that "what people" want is often the wrong view of things. Fox News (yes I brought that in) is a classic example. They "make" the news the viewers want... truthful or not. It is no different than the movies. A western from the 1930s portrait the Indians as savages that need put down by the heroic US military. That was the view of the American people, thanks to biased history books and basically a whole country in denial. The reality is that the US military and politicians of the time were brutal mass murderers that committed genocide. Problem is, over the century and a half, the people involved.. Custer, Grant and so on, are seen as American hero's who battled the evil Indian and that view is hard to change. The Japanese are another classic example.. their WW2 record. In total denial.
Movies themselves dont have to be 100% factual per say, but when you make a movie about a historical point in history, then some sort of accuracy is a must.. else it is just another tired propaganda movie....
Let me give you a good example. Many American's believe they won WW2. They were the heroes coming to save their poor European cousins. War movies are always from the American point of view and rarely do we have one from the British/Canadian/French let alone the German. The American trooper never does anything wrong and we both know that is simply not the truth or factually correct. This view is because of their history books and their movies.. especially their movies.
Now the actual factual part of WW2 is a whole different picture. Yes there were many American troops in Europe, but in sheer numbers there were more Russian, and the Brits also had almost 6 million under arms in WW2. And on the battlefield it was the Brits and Russians that were the unsung heroes of the war... take the breakout of Normandy. Movie after movie depicts the brave American GI being the key to breaking out Normandy and start the German retreat across western Europe. Now the reality is that it was actually the British that made it possible because they held a huge amount of German troops in check and defeated them at Caen. The American's basically met very little resistance once they got of the beaches... and yes here they got a lot of resistance. But no one talks much about the battle of Caen in the importance of D-Day and the break out of Normandy. It is the stories of the 101st Airborne, or the 82nd Airborne, or the stories from Omaha and Utah beaches that are used over and over, where as the British and Commonwealth landings on Junno and Sword and Gold are rarely talked about. And when talking about Omaha and Utah, it is rarely mentioned that much of the hardship on those beaches was due to American incompetence rather than planned German resistance. Once in a while it is mentioned in D-Day movies, but is quickly glossed over. Or look at the Mulberry harbors... ever heard of them? British invention, highly successful and key to the landings... the American's dismissed these harbors and the one they had was destroyed to American arrogance and incompetence (they basically did not follow the instructions... ). But without the British Mulberry harbors, then the invasion would have failed. Or the funny tanks that cleared mine fields, or the floating tanks.. all British inventions and yes the American's thought they were failures... because they lost a lot of troops in them.. and they never mention that the troops died because the tanks were released too far from shore... and yet today... the US armed forces use the very same designs in their tanks to clear mines or get tanks to shore.. ironic eh?
Take one of my favorite war movies.. Patton. At the time of the release it was heavily criticized by many because of some of the context. The Battle of Kasserine, one of the biggest defeats in American military history is mentioned in the movie as it is the key part for the appointment of Patton. They show dead GI's... wtf! They show dead GI's being stripped by the locals. They show incompetence undisciplined American troops. All factual and all shocking at the time. And yet they dont in the movie go so far to state that the defeat was due to incompetence from the military brass at the time, combined with lack of training and basic arrogance. But they do portrait the American solider in a negative light.. well barely, which at the time was revolutionary. Up to this movie.. Kasserine was rarely mentioned.. wonder why..
Ever wondered why there are so few movies about America's involvement in WW1? Think about that a bit..
It is things like this that over the last 100 years of cinema history (and especially American cinema) has formed false views of history that we only now are slowly trying to change.
More and more movies are more and more accurate and differ from the usual set view of historical events... there is a long way to go but it is a start.