Hmmm. What in the Tolkien canon, or in his letters, suggests that any of his works are propaganda?
There is evil in the world. Auschwitz was evil. The Famine-Genicide in the Ukraine was evil. The Gulags were evil. The death of (tens of) millions of Chinese during the Great Leap Forward was (the result of) evil. One could go on. Many people, and I'm one of them, would reject any nuance that tried to diminish and explain away these evils. Do I want to understand what I can do to prevent them? Sure.
There should be room for both nuanced stories and grand narratives.