I'm not sure I agree with your car analogy, but your basic point I think is correct.
Why not Jim?
The best selling car in 1980 was an Oldsmobile Cutlass. At the time, people must've thought it was a pretty good car in order for it to claim that honor.
Fast forward 38 years, and the best selling car is a Toyota Camry.
Back in 1980, the Cutlass was a fine car. However, put that car side-by-side with a Camry today, and it's a pretty laughable comparison as the Camry is going to be better in every measurable way. Faster, safer, more luxurious, more efficient, etc. As time goes on, technology improves and as that technology improves, expectations and the status quo shift. People today expect more out of their vehicle than they did back in 1980.
It's no different with lenses. Back in the day, the Ai and Ai S lenses were great. However when you compare them to a modern lens they employ lackluster coating technology, lack the sharpness of modern lenses, have much lower contrast, poorer flare performance, worse chromatic aberration performance, etc. In the past ~40 years, peoples expectations of the level of performance that a lens should deliver have changed, which means that lenses that we once thought were fine, may no longer be the case because of a shift in our expectations.
I should note that some people want that "vintage" look provided by older glass (flaring, low-contrast, soft rendering), but if your goal is image sharpness and outright image quality, then modern day lenses are the way to go.