Of course, it's a rarity that a ref gets mauled in the middle of action or slammed into the boards, but it does happen. And although anybody can lace up some skates and throw on some stripes, the agility and precision it takes to be a good ref is something that is extremely hard to come by.
It may seem intense for a player to be on and off the ice every two to three minutes, but a referee is on the ice the entire game and must follow the puck wherever it goes. On average, a referee skates about six to 10 miles every game. Only stopping during time-outs or after a whistle. It takes someone who is in fairly good shape to be able to skate well enough to follow the puck and make appropriate calls.
Another thing that is vital for a good referee is experience of the game. In this area, knowledge and EXPERIENCE are two different things. Obviously, even though I know all of the signals, I know what to call and why, and I know how long a player should be in the box for what penalties, someone who has actually played the game will be a lot quicker in making calls, because it's something they've seen their whole lives. They have keener eyes.
I have met, probably the worst hockey ref in history, literally. In fact, he works at Ice Town. But the he is so bad is because he has never played a day in his life. He tried starting a roller hockey team when he was younger, but playing roller is almost detrimental to someone who wants to play ice. And one day I'm sure he told himself, "Hey, I like hockey, and I own some skates. I should try reffing to make some extra cash!" Bad decision.
Another thing that makes referees so respectable to me is the crap that they have to deal with. There is nothing on this earth worse than a hockey parent, there just isn't. Because of the fact that they spend so much money to get their kid to play, it's an abomination for them to get a penalty. No matter how obvious the infraction was.
Although I do admit, there are some pretty horrible hockey officials out there, such as said Ice Town kid...it's not an easy things to do. So before someone tries to argue a call or just jumps on the band wagon and hates referees of any sport, try throwing on skates and stripes, beware that it's more difficult than it looks, and there's no crying in hockey.