I don't really care if it's the 1970s or 1980s. The point is that I couldn't believe my eyes when I saw footage of old hockey matches where the players had... no helmets. As if it were faked or something. It seemed like insanity to me, and I even heard somebody suggest that they used to consider the idea of wearing one to be "sissy"! As in, it was a manly pride thing to not wear any helmet for protection... which just seems beyond stupid to me.
Soldiers have had helmets in wars/battles/while training for a very long time, even though they can easily be shot in the chest or elsewhere with no protection. Manly construction workers don't mind (to the best of my knowledge) wearing a helmet at the construction site due to the risk of falling hammers and whatnot.
On the other hand, I have taken up bicycling again recently after years of not leaving the house, and I don't feel the need to use a helmet even though I really thought I would feel scared for my life every second prior to actually sitting back on that saddle and pedaling around. Maybe it's the same thing here: you imagine that it's oh-so-dangerous to be on the ice rink without a helmet, and enlarge the danger in your imagination, but in reality, you very rarely hit your head even if you do fall, and the hockey puck is very unlikely to come flying towards your face in practice?
I won't pretend to be any kind of sports expert or even fan, but I'm not aware of serious injuries to the head being a major issue for ice-hockey players prior to them switching to requiring helmets. Then again, maybe that was the reason that they did start using them?
The fact that they didn't use them for so long suggests to me that they weren't really necessary in the context of playing ice-hockey. What changed?