70s cinematography cont.

Commenter Josh comes to the rescue and notes that László Kovács claims innovation of the lens flare trend in 70s cinema. I'll accept that but still wonder what ultimately brought about the trend. (a- innovators have a broader context, b - innovators aren't always imitated).

To that end, here's some insight from David Cook: 

Cinematography in the 1970s acquired a distinctive look that was characterized by the use of heavy lens diffusion, the introduction of fast lenses that could register images at very low levels of light, and the practice of "pushing" the film in the lab... The increased use of diffusion was an aesthetic phenomenon, seemingly a reaction to the high-image definition made possily by recent refinements in film stock. (Lost Illusions 355-6).

Now, diffusion is clearly a different effect than flare, but the underlying logic of aesthetic differentiation may be the same. Flare may be a way of both showing off the capabilities of the new fast lenses and processing (the difference between 70s and 60s cinematography registers in part by the ability to shoot existing light). At the same time, it is a way of muddying up an image that seemed too crisp. Mind you, that's hypothesis. We'd need a closer look at how any given DP used flare or how it was received.