And I'd go beyond that, and blame the mumbled lines for our lack of interesting quotes. It's a lot harder to have unexpected turns of phrase, speech patterns, or novel vocabulary choices when the audience is struggling to understand even the most basic, predictable sentences.
[1] https://www.slashfilm.com/673162/heres-why-movie-dialogue-ha...
Edit: for people mentioning audio mixing and stereo, that's only part of the problem. Even with my (admittedly cheap) 5.1 setup, I sometimes miss most of the dialogue in some scenes. I think the change from theatrical to more realistic enunciation is also to blame.