While many people do not find fighting during hockey justifiable, I feel that such people don't understand the importance of fighting in hockey. If you take out the fights, you open up the game for more illegal fouls and checks from behind.
Fighting helps to keep the game clean. A hockey game is like a pressure cooker, and fighting is the relief valve. Without it you have anarchy on the ice. There is an element of violence in all sports. Hockey is the only one to have an honorable way of dealing with violence, and that is fighting. Two opponents square off and settle things.
The fans enjoy a good hockey fight. Two things really excite the audience of a hockey game, a goal and a fight. When a player starts to slash or elbow a team's top skilled player,a player from that team will challenge the attacker to a fight. This helps to protect the highly skilled players from injury. The most coveted players in the game today are ones that are highly skilled at playmaking/scoring and can fight.
Since hockey players are on blades and have sticks in their hands, and collisions are constant. With so much physical contact, there are bound to be disagreements, which makes fights inevitable. After a fight the players are penalized, and the game continues. No one wants to see players incessantly slashed, butt ended or elbowed to the face. This fighting plays an important role in the game.
Fighting is also used by coaches as a tactic to breathe life into a team. If a team is down a few goals and nothing is going right for them, an enforcer is sent out to throw some hard checks into the opposition. This will inevitably cause a fight. A good fight can wake up a team that is struggling.
Many fights happen out of sheer frustration. Most coaches on the winning team will keep their highly skilled players off the ice near the end of the game and replace them with team's tough guys just for this reason.
Hockey fights are different than other forms of fighting. For one thing, they are 100% real, not fake. The players are not trying to score points, but rather crush their opponent. The player who gets in the most punches and lands on top is usually declared the unofficial winner. Another aspect of hockey fights that sets them apart is that the opponents are on skates. Balance is crucial. Many times a smaller player with better balance will have an advantage over the towering player.
Thus, we come to the conclusion that hockey players will fight and audiences will cheer them.