I think the current shaky cam trend started with Saving Private Ryan. The excessive use of lens flares, I'm not sure.
Traditionally, lens flare was considered an error and was scrupulously avoided by Hollywood cinematographers. Lens flare became, for lack of a better term, "hip" in the 1960s. Ironically, it was thought to enhance verisimilitude, to create a documentary-like realism -- although, of course, it's a technical artifact created by reflections between multiple elements of the camera lens.
Compounding the irony is that, with today's digital photography, lens flare is often a CG effect added in postproduction.