I think the no penalty number is mildly acceptable. Part of the reason for suspensions is the fact that referees are going to miss incidents behind the play and/or away from the puck, and that linesmen are not often authorized to call penalties. I think what's more egregious are the number of minor penalties - penalties where the referees, in real time, couldn't determine that the play was dangerous enough to merit a major penalty (and I assume that all suspendable hits are eo ipso major penalties). Still, between the no calls and the minor penalty calls, of the 34 incidents the NHL deemed suspendable plays, only 41% resulted in a major penalty power play for the opposing team. I find that's far too low, especially since that's often the only real benefit a team might get for a dangerous/suspendable play. Here are a few ideas that are aimed at either trying to change this practice:
A. If the suspension is minor, suspend players only for games against the team they committed the foul against: I've heard this proposed elsewhere and I kind of like the idea. It's not really fair if, say, you're locked in a playoff race with team B, and yet one of team C's best players commits a foul against your team, that player gets suspended, then team C plays team B next game. I recognize this is a rare scenario, but the point is that suspending a player for only games against the team against which he committed the foul makes it fairer. Perhaps the aggrieved team could pick which games the suspended player is set to miss, for instance.
B. Allow linesmen more latitude to call penalties. I'm not sure how I feel about this, because the linesmen have their own job to do, but I feel that those two sets of eyes aren't used often enough by the other referees.
C. Change the penalty structure. Doogie2k suggested this on mc79hockey - the OHL makes head hits a mandatory 2 minute minor, plus a 10 minute misconduct. I'd apply this rule to illegal head hits, boarding, elbowing, and checking from behind. It seems ridiculous to me that often a little tug on a player's jersey with a stick and a violent, illegal hit into the boards usually draw the same penalty. Furthermore, I wonder if a 5 minute major is really the best way to penalize a team whose player commits an egregious foul. Perhaps the penalty should instead be an automatic 2 minute 5 on 3 power play where a goal scored does not change the manpower situation. Of course, one is faced with the problem that referees hate impacting games even when they should, and therefore we might see even fewer major penalties called.
These are all just ideas - I think we can recognize that the NHL is trying, at least a little bit, to alter the culture. I'm just not sure that outside-the-box ideas will be broached or considered, when perhaps that's precisely what's needed to alter the culture.