We've got explosions, actions, ki blasts, hordes of dead extras, and so forth, and the person leaving such destruction in their wake is usually the hero. It's a popular idea - the hero can be as violent as he wants, no problem. Unfortunately, when you examine it, this brings in loads of trouble for good continuity. So, let's dive in. That's how it works, case closed.
Violence has results in the world, at times unpredictable.
Committing violence has results for the committer. People assess risks - including that of other people, and a violent person is a risky person. Violence takes up time, energy, and is risky. The problem, simply is, heroes who use violence are often poorly written, ignoring the results, causes, and implications of violence. The act of violence affects the actor, as does encountering violence.