Was not wearing a bra really that common?

That's pretty unfair.

Especially considering that recent studies say bras increase boob sag over time. They don't serve any real purpose but to decrease the chance that someone like you will make moral judgements on women as a whole just because they don't want to wear an uncomfortable bra.

I personally see man nipples all the time, but women are expected to hide our nipples. Sexist rubbish. Nipples are not sexual until someone chooses to sexualize them. We all have nipples. Female nipples purpose is to feed babies.

But in this case, I think nipples were shown because that's what the male audience expects in their slasher films. They want the camera to pan down and show every female cast member's tits, and butts. For me it was amusing in a satirical way but also annoyed me as a women, that these actresses can't even get acting work unless they are willing to exploit themselves. While I stand up for women to be able to go topless or braless, anywhere a man can, I can see the difference between the expression of freedoms and just showing women half nude because men want to jack off to their horror films. Personally I don't find horror and killing and death to be sexy and I think it's disgusting that so many other horror fans think they must go hand in hand.

And I get the underlying peeping tom fear, that does go hand in hand with many horror films, but the shower scene especially was there just because the film makers want extra nudity. The killer wasn't even in the shower area, so there is no reason for it besides just having female nudity for the audience that

That's exactly what I was thinking when watching this film.

Every time a woman took her top off. "I wonder how common this actually was at the time this film was made", I thought.

I noticed that after not having watched this movie and Silent Night, Deadly Night for many years. It seemed more like a 70's thing to go without, but just about every murder in both movies didn't feature one. I'd say it fit the films more to have the killer just stab away without anything covering. Plus, too, there was always the idea that the fully-clothed "final girl" would likely prevail over the lesser-dressed "slutty" friend.