Scoring is down because of expansion. Back in the day, there were 21 teams and 16 of them made the playoffs. This turned the entire regular season into a glorified exhibition. It didn't really matter if you won or lost a game. Who cares... so no one played defense and coaching wasn't as strict and everyone was just out there trying to razzle-dazzle all the time. Scoring went down in the playoffs because the games actually mattered.
These days, it's A LOT harder to make the playoffs, so teams can't screw around like they used to. It's a lot tighter and a lot more competitive. Every game means so much more than it used to.
Anyway, I think there are a few easy things you can do to increase scoring. One, switch the long change to be in the 1st and 3rd periods. Second, figure out a way to drastically reduce the amount of offsides calls.
It's funny, because they call icing so loosely... as long as the player is kinda sorta nearish the red line, then whatever, or his stick crosses over the red line in his follow through... no icing... but if an attacking player 45 feet from the puck carriers skate is .25 inches over the line before the puck... the whole play is called dead.
I don't know what the answer is, maybe have a 3 foot wide line and as soon as the puck goes over one end of it, it doesn't matter where the attackers are? That way they can be ahead of the play, and it still stops guys from cherry picking and keeps the spirit of the rule intact, while also allowing for more exciting rushes to actually not get called down.