As an interesting aside- there just wasn't a whole lot of innovations with the bicycle, between saying 1950 to 1980. This was the TdF winning bike from 1947:
Coppi
TdF bikes from 1978:
Hinault
The bikes look really similar - with steel lugged frame, down tube shifted derailleurs, toe strap pedals, tubular tires and side pull caliper brakes. There just wasn't too much in the way of innovations during those years. In a sense, a lot of what we think of as 'classic bikes', are a product of those 30-40 years of stagnation.
In the early 80's there was a big push towards aerodynamics. From there we had an explosion of new technology from the mid 80's to mid 90's- aero brakes, hidden cable routing, dual pivot brakes, brifters, clipless pedals, carbon fiber, aluminum, titanium, etc.... Again from the mid 2000's to the present time we have yet another big wave of innovations with electronic shifting, power meters, tubeless tires, hollow cranks, carbon fiber wheels, aero everything.
So one could think of the circa 1980 'classic bike' as a time tested, timeless, well rounded product, or you could also think of it as a hopeless dinosaur from an era of stagnation.