I think that it's been happening for a while. Movies in the 70s and 60s tended to have more pause in the dialogue, more silence than movies in early 2000s.
Take a movie like the Godfather, it had a 8.4 seconds average shot length compared to the Departed 3 second average shot length.
I've noticed my parents no longer having the patience for movies with longer average shot length despite having been young during the era when movies were less fast paced.