I was a hockey coach, so I'm not sure this might be a reason. I've thought that the shot clock has made teams take more shots in general, which they wouldn't have in the past. We always told players to get a shot on goal, as good things will happen, rebounds, goalie mistakes, deflections, etc. We've all seen players not take a reasonable shot to make another pass. The sheer increase in attempts is going to result in additional scoring.