Last year I got into a discussion with a few friends on the subject of Netflix testing out adjustable playback speeds on its movies and shows. Most people I talked to were generally apathetic (“I wouldn’t use it anyway”), but a few did not like the idea at all. To them, being able to change the way that something is viewed to that extent would go against the artist’s artistic vision, and interferes with the media as it was intended to be consumed.
No matter what kind of art a person is creating, there’s a lot of thought behind a finished product. For movies, the impact of a scene may be demonstrated with the tempo of the music, the movements of the camera, or cuts (or lack thereof). Being able to change the speed the movie is viewed at could completely change all of the carefully chosen and planned components to a scene, potentially changing the way the movie is viewed entirely or taking away its impact.