You can't have a player who just sits on the bench for all but 5 minutes of a game anymore. Everyone has to contribute. If a guy can fight, but chip in some goals and assists, every now and than, bring him on, but if all he does is fight, there is no room on the roster. You wouldn't want him to be in every game, because he wouldn't always be needed. And, you can't always predict exactly which games he would be needed.
Like it or not, the last 4 Wings' teams to win the Cup all had a fighter on the roster during the regular season. As Babcock says, "they keep the flies off" the stars.