One reason for this is these shows don’t tend to show the morally questionable things a resistance has to do to be able to win. So it’s a lot easier to side with the resistance in Star Wars when they’re just fighting conventionally against the empire. I think a much better depiction of resistance can be seen in Star Trek Deep Space Nine with the Bajorans. They fought the Cardasians in a guerilla war which often led to civilians on both sides being killed. It’s a lot more murky but the Bajorans are still unequivocally viewed as the good guys since it was the only way to resist and get rid of the Cardasians and stop them from killing their people.