I believe that the fans of the NHL are the biggest losers in the lockout. The inability for players and owners to avoid a contract at every point in which renewal comes up goes to show that there is dysfunction in the league and a lack of ability for compromise in a meaningful way. The fans miss out but so do the businesses that are created around them. The business owners are often fans too and they need an apology more than anyone!
They absolutely should apologize to their fans! They should do it as a league, and they should do it in a way that makes it clear that they are really sorry for their behavior. They also should let the fans know how they plan to prevent something like this from happening again in the future.
Fans don't want to see shallow messages on ice, or ads in papers. They want to see that the issues that plagued the league are being addressed, and steps are being taken to make sure it doesn't happen in the future. It's kinda like saying you're sorry for breaking your mom's vase--unless you actually stop throwing that ball in the house, then your words are meaningless.
The NHL knows the damage they have done. The fans know the sport is being ruined. Apologizing for such is just a slap in the face to an angered fan. After delaying the season over greediness, causing hundreds of small businesses to close down and the cities overall economy to struggle, you want to offer an apology? No. The NHL is lucky people are still watching. Don't insult their intelligence with something so insincere.