Art leans left. The suits role is to keep that leftism from getting too overt, while raking in the money.

Another aspect: The common theme of the universe naturally leading to the resolution of injustices is a very addictive form of hopium that lulls individuals into inaction in real life. Like a lot of underdog stories. It really doesn't matter if the fictional baddies are right-wingers, so long as the content prevents everyone from doing anything about the real life baddies.

And a final aspect: Who needs to be portrayed as good when they're rich and powerful? It's mostly people who rely on other people - rather than the privileges of money - who benefit by being good. The system already protects the rich. So when many people get rich, they stop caring what others think about them. It doesn't matter for their own quality of life anymore. And then people come along and want to to make a rich studio exec a lot more money by creating a show where the rich person's likeness is a baddie? The execs know that formula sells like hot cakes - easy deal!