The lockout during the 2004/2005 season had devastating effects on the NHL. Many fans were lost and did not care to watch the next season. This hurt the owners as their income from tickets and marketing were way down. The lockout also hurt the players because the lack of revenue caused the salaries of new contracts to be nearly cut in half. The only positive to come out of the lockout (for most teams anyway) was the salary cap because it kept large market teams such as Detroit from trying to buy a Championship by stacking their lineup with high salary superstars.
The league has just now been starting to recover and regain the popularity that it had lost. Another lockout at this time would be especially devastating just 8 years later and could cripple the league by destroying their fan base. I agree with the players association on the issue as they would be the ones ending up with they decreased revenue. The proposed contract restrictions, such as a maximum of 5 years on a contract and teams holding a players rights longer through restricted free agency, seem unreasonable when compared to the other leagues such as MLB, NFL, NBA. There are no such restrictions in the other big three. However I do hope both sides can give a little bit and come to a compromise. Hopefully they learned from last time that greed is not the answer, because as we seen neither side really came out a winner.
Besides the financial issues from fans abandoning the NHL ship, there are other issues that a lockout would cause. Many European players, especially Russian ones from the KHL, such as Vladimir Tarasenko, will return to their European and Russian teams in the event of a lockout. If they leave who can be sure when they will come back. Another devastating thought for Blues fans is that the team is in their prime and coming off a great season and it would be a shame to throw away a year where they have a chance for the cup. Hopefully the issue is settled before the start of the season, or worst case just a month or two late such as the NBA, because the loss of a whole season benefits no one.