George Orwell disagrees.
Perhaps its adults books which should replace humans with animals?
I disagree with OP RE BSG.
It was not about morality in general it was directly referencing our current views on morality, specifically the Iraq war.
But do agree subbing in animals/zombies/aliens for humans allows movies to get away with more.
In particular, people who read historical fiction deal with these topics all the time.
Stories about German occupation, whether real or made up deal with it. French revolution is all about violence.