An afterthought. Many of the '70s lenses were re-designs of the '50s, using improved computational processes, new glasses, and ( important ) in consideration of efficient production methods.

Lenses like Sonnars, which were unable to be adapted to the slight retro-focus designs needed for a 50mm to work with an SLR, had been weeded out of normal production in the 1950s. They were still found in short telephotos ( Nikon, Pentax... Hasselblad ), but had generally been replaced by Planar style lenses. In the '70s, the evolution was complete. The Sonnars were not suited to the manufacturing styles then adopted, which DID suit Planars ( and Plasmats in the LF domain ).

Nearly all 35 mm lenses, therefore, from 50mm to 200mm were now all the same basic formula, with balancing of the design to suit either aesthetic or financial concerns of the maker.

In other words, by the time the 1970's lenses were on the market, there were only slight differences between them. Some lenses ( 105 Nikkor or 35 Summicron, for example ) were standouts, but there were no longer 'signature' looks.

Recently, Leica has produced some lenses ( 35/1.4, 75/2.0 ) that are significantly different in performance and appearence from the lenses of the '70s and '80s. A few lenses from Nikon ( 105/2 DC ) are a departure from the 'look' of earlier lenses.

By the mid 1970s, most lenses were of similar design, manufacture, quality control, and varied only by price point. They should be seen as the 'baseline', rather than as 'vintage' lenses. Chances are, the lens on a new camera will be a '70s design - unless it is a zoom. And if you want a different look, dig deep into your wallet for one of the few 21st century lenses, or go back to a pre- 1970 lens.