4 on 4 OT playoffs would see me saying goodbye to the NHL.
I only watch the playoffs as it is. I used to know every player in the NHL and watch every game until the mid-90's but lost interest. In most sports btw, for a variety of reasons.
It's the playoffs. Scoring is always lower in the playoffs, teams play much tighter and match line vs line on a level beyond the regular season. Playing the same team 4-7 times in a row leads to tighter games as coaching staffs study their opponents to adapt their on ice strategies and limit scoring opportunities. The salary cap has also introduced a level of parity in the league as can be seen in the standings of this past season. Many teams are fairly evenly matched in the new NHL leading to tightly contested matchups.
Would a bigger ice surface improve scoring? Maybe, maybe not, coaches would adapt their defenses and play to minimize scoring even on a bigger surface. Teams are not coached to score more goals but to not let in goals these days, or so it seems to me compared to the 80's. Most of today's NHL athletes are playing at the same skill level too. There used to be an obvious disparity between the A-players and B-players in the NHL where a Gretzky, Orr or Bossy could exploit the inability of a defenseman to keep up with them. Most "fighters" don't make the NHL anymore thus removing one pylon from the lineup and it's rare to see a player deke another player out of his pants which was fairly common in the past.
Also, today's goalies are highly skilled, bigger and more athletic compared to goalies of the past and commentators regularly say the only way to beat goalies is traffic in front of the net which is the new strategy. Yesterday's goalies did not cover the net as well as the 6 ft plus goalies we have on every team in the NHL today. Not to mention their giant lighter goalie pads, and supersize blocker and glove. The net size consideration might have some legitimacy.
I would consider banning shot blocking to improve scoring. The act of defensemen dropping to the ice is a relatively recent phenomenon in the NHL over the past 15 years or so. There were the odd players who did this but now everyone does it. This behaviour was not a factor in the past and shots on net reached the net while some were inadvertently blocked by someone standing in the path of the puck. Some games have more shot blocks than shots on net, it's crazy. There is still plenty of puck movement but players can't get the puck to the net with all the player's covering the ice surface.
Regardless, the NHL is a joke in the sense that every year the GM's have a meeting to tweak the game and nothing helps. Improving the officiating would go a long way to improving the game and the attempt to remove clutching and grabbing is a good start along with the illegal crosschecking of players in front of the net. MLB, NFL and the NBA don't meet every season and consider lowering the pitcher's mound or basket,shortening the distance between bases to enhance base stealing, widening the field or expanding the size of the basketball court or net to improve scoring or fix the game.