A lot of air travel was for work because it was so expensive, thus the suit wearing. You can hunt around for some pictures of flying in the 60s and 70s and fine no shortage of people in vacation gear or 'street' clothes but back then even street clothes were more formal (you'd toss on a sports jacket or fedora without thinking twice about it for even yardwork). A lot of what we see today in photos are carefully crafted PR and marketing pieces. People back then didn't have smartphones to photograph an average cabin, so we see these wonderfully staged photos of a gorgeous stewardess carving up a turkey for a well-dressed and posed family, which isn't exactly something common in flight. Do you really want someone on an aircraft that can jostle at any time holding a carving knife at your neck's height?
Also, that's not a plane, its a Hollywood set. You can't open the door mid-flight as the pressurized cabin won't allow you, at least past a certain year when all airplanes standardized on the inward opening door. Everyone is thin and glamorous looking because they're actors. Everyone is well dressed because the costume department made it so (no ill fitting suits or out of fashion dresses and skirts). No crying babies because it would ruin the drama. No elderly people having a coughing fit. No dirty looks if you happen to have the wrong skin color.
I also don't see how people smoking is supposed to be this wonderful freedom loving thing. As someone old enough to have been around where people smoked next to you all the time in just about any social setting, it was disgusting and unbelievably rude and entitled, on top of being a major health issue for those exposed to second-hand smoke, especially children. I'm not sure what the GP was implying but you don't want to go back to those days. A recent week in Japan reminded me of my childhood and that aspect of my trip was fairly unpleasant.