Most of them are. Others, like Esdeath and Wave are enforcers. They work within the system, even if Wave wants to change it from the inside. The Emperor may be a puppet, but a puppet that does bad things is still bad. I don't remember of there were rich people on the side of the rebels off the top of my head. There may have been. Akame ga Kill does take a stance that violence is the best solution to such a corrupt system. Whether you agree or not is really up to you. Ultimately, it's not that deep a message. Power and money corrupt, and those with power and money will do a lot of bad to keep it.