Won't stop headlong slides into the boards from accidental trips. I know what you're after. I went to Flyers games in the 60's when the only guys who wore helmets were named Jean Guy something or other.
The push for helemts began when Bill Masterton of the Minnesota North Stars died after he fell and struck the back of his head on the ice during a home game with the Oakland Seals in 1968. Helmets finally became mandatory in 1979, but the NHL had its biggest surge in popularity in the 80's, so I don't think that brain crates have much to do with the present "troubles".
Bonus trivia: Andy Brown of the Penguins was the last goalie to play without a mask, against the Atlanta Flames in 1974.