When comparing "flying then" to "flying now", you need to look at the real cost of the flights. Yes, the experience in economy class has got worse, but the cost of the ticket has also significantly dropped. In 2021 dollars, the cost of a round trip air fare has basically halved since 1979. You could buy a business class ticket now for a comparable price to economy back then. https://www.airlines.org/dataset/annual-ro…
I don't think that number will hold up if you include square feet of personal space and lbs of luggage that might need extra fees.