Enforcers are the great placebo of the NHL. They persist because everyone thinks they do something positive (intimidate other teams, "protect" star players) even though there isn't a shred of evidence that they actually accomplish anything.
The goon in the modern NHL is a castrated beast. He bleeds goals against and his every move on the ice is tracked by nervous eyes and quick whistles. Fines and suspensions are the primary fruit of his labor. He is rendered impotent by two simple letters: "no". Pests laugh in the goons face. All that's left is the occasional, ritualistic dance with another anachronistic brute before the hoots and hollers of the crowd. It's exciting, it's gladiatorial, but...I doubt it helps win hockey games.
EDIT - Just stumbled upon this expansive essay on the subject by E over at Theory of Ice. Similar sentiments are expressed more thoroughly:
The power of a fight to resolve violent tension in a hockey game is, in essence, the ultimate placebo effect. It works not so much because of anything it does in itself, but because of what the concerned parties believe it does. As such, it’s a highly imprecise conflict-resolution technique. While there are many incidents one could point to where two fighters thwacking at each other after a dubious incident provided satisfactory resolution to both teams, one can also point to at least a few very high profile cases where a fight not only failed to resolve tension, but perhaps escalated it. It may indeed be a safety valve of sorts, but it’s a defective one that can fail at any moment. However, whether or not fighting serves the function people claim for it is somewhat secondary, because what matters for professional hockey-fighters is that placebo effect- the belief that it can control the inherent danger, violence, and unpredictability of the game. Surveys occasionally show that players generally like having a fighter on their team- not, perhaps, because he actually makes them any safer, but because he makes them feel somehow safer.
