So wait - what about boxing and UFC? Where the goal is to knock the opponent out, but once the fight is over most fighters hug and congratulate each other?

It is not the same and it bothers me that people don't recognize this in the least. There wouldn't need to be fights in the first place if people played hockey like sportsmen. Boxers have agreed to a fight, that is the point of the sport. Hockey players have agreed to a game of hockey and when they get irritated or frustrated they start getting physically violent and stop putting pucks in the net.

Hockey players are there to score goals into the net or save them. Why fighting needs to be part of the sport is beyond me? Rugby, Football and Soccer players don't need to scrap like children or drunks at the bar every period so why is it only part of NHL Hockey and not the Olympic if it's so integral?

Why don't all sports have this dynamic if it's so critical. Hockey isn't the only sport where people get passionate, however, it is a sport that teaches you to level your opponent and beat the shit out of him if you do get passionate. Other sports, generally don't.