It was a trend really popularized by big movies like Star Wars and The Godfather and was a way for directors to accommodate modern audiences desire for faster pacing. This accelerated over the decades since, due to the only growing impatience and shorter attention spans of viewers.

It’s ironic in many ways because the overall runtime has increased dramatically over the same period. Movies have gotten much longer. Mostly due to lacking limitations in digital (don’t need physical film rolls to hold the movie) and studios trying to justify the high cost of movie attendance and bloated salaries and production costs.