Air travel did have a Golden Age. There was more space, classier interiors and bolder designs. You don't even have to go back to the 50s and 60s to see that. Here are some of the actual cabin interiors for the Boeing 747s in the 1970s. They are awesome.
The idea of the Boeing 747 started in the 1960s, when Pan Am asked Boeing for 400-seat plane. Pan Am's chairman Juan Trippe had a flying ocean liner in mind, a double-decker jet. But the design team at Boeing didn't think this was a good idea. They favored a wide-body design because, back then, it made more sense from an engineering, economical, and safety point of view. The Airbus A380 changed this decades later.
But back in the 60s, that was the reality. To demonstrate their idea, they built this prototype of their idea for a 400-seater's economy class:
Ultimately, the actual 747's economy class didn't look exactly like that, but it was pretty similar, with the same seat configuration and similar headroom. In fact, other planes of that era and later had a similar headroom because they didn't have overhead bins, as reader Stalionblue puts it:
There is some truth to the headroom thing. Many early widebodies did not have the center row of overhead bins and the bins tended to be much smaller than today's. So they did in fact have a lot of headroom in the middle. The pictured mock-up stretching the truth, however. Here's a Cathay Pacific (Lockheed L-1011) Tristar interior from 1981 without center bins:
Pretty damn airy, right? Here's another photo without bins (and with flight attendants):
In part, you can say that it was us and our stupid carry-on bags that screwed airplanes.
What about the 747's first and business class? For the first class Trippe actually got some of his double-decker vision in the final 747, with its famous upper deck. Boeing proposed these lounges, which were not much different than the actual upper decks, as you will see below:
Here are some more photos of 1970s interiors in real planes from Pan Am, TWA, American, United, National, Continental, Iberia, JAL, and SAS:
Even the storage areas looked like a scene from 2001 Space Odyssey.