Well, not always. Oliver Stone makes some good ones! However, it is nice to see non-preachy ones like Romper Stomper, the portrayal of Australian Neo-Nazis (and also the series).
Well, the thing is Romper Stomper still gets the message across in the end to most people, and I can say the same about the German naval movie Das Boot (The Boat). The Romper Stomper movie and series both end in terrible violence and a lack of resolution for either side, and Das Boot ends with a bombing occurring tragically after a highly unlikely escape.
On the other hand, American History X was preachy. Glory was preachy. It’s pretty easy to be cynical about these films because it’s difficult to not notice the sanctimoniousness! But that doesn’t mean they weren’t great and moving films.
However, to a conservative these films might be annoying due to their condescending tone. It’s so much cooler when a non-condescending movie changes the mind of someone who you’d think would never be so affected.