Today it is a cattle farm.
Yes and no...it’s more that we’ve added a class of service that didn’t exist in the past, although we kept the same name (coach, or economy). And in that service we do pack in the people. What was coach back then is now Business/First Class, and the prices for that level of service, if anything, is less now (i.e., it’s cheaper to fly Business over the Atlantic/Pacific today than it was to fly coach on the same routes back then).
One reason we didn’t have our packed-in coach sections back then was very simple - we didn’t have the engines, the planes couldn’t handle that much weight. It wasn’t until the engines made their huge improvements that the airlines started packing people in (as a side note, today’s planes also go nearly 100 mph slower...due to those fuel-sipping engines).
As to myself, I like the option of either paying what I would have for coach in 1970 and flying first class, or paying far less and having much more money to spend at my destination. Like just about everyone else here, I chose the packed-in option.
But, as a tidbit - for people living on the West Coast or near NY City, you can fly today in coach to pretty much any major city in Asia for under $600 round trip, sometimes even as low as $400, and that always includes 2 checked bags, and full meal/alcohol service. In other words, it is often less to go to Asia than it is for domestic travel. Try getting those prices to those destinations, even if not inflation-adjusted, back in the ‘golden age’ of air travel!