The rules are structured in such a way that it is not actually violence in the most understood form. Rather, it is acting and mere agreement amongst players to put a show on for all of the spectators. This sport is does contain some violence in a controlled atmosphere. Currently, hockey players know that there will be some violence within the game. Violence is part of the sport and always will be.
Nobody condones or wants to see a majority of the game filled with fights.
But there are times when two players need to vent some aggressions. We currently have violence in other sports like Boxing, which is one of the most violent sports around today. It can continuously be sold out and draws spectators of all aspects. This is not wrong, it is to be expected. It does not take a genius to say that is based around violence.