Think about your favorite scene from a movie or television show. Then think about famous scenes constantly referenced, whether humorously or part of a top 10 list. Chances are the music played during the scene is an important element of that memory.
The practice of using individual songs from artists that were not expressly written for the film was not always done. "Easy Rider" was the first film to engage such an idea with the music and film becoming inextricably linked. Ever since, directors have been using this to help them tell their stories. Masterful combination of an emotional moment with deeply affecting music is not just enjoyable; it can also have a lasting impact on our musical tastes.
Discovery
There are several ways in which this happens. An obvious way is being exposed to songs for the first time, whether it is a brand new song or a forgotten oldie. Many of us have found favorite songs this way, and may have never heard it otherwise. There is an enormous library of recorded music, with few of us possessing the time or resources to explore even a fraction of it.
A further extension of this is when we hear a familiar song, but come to perceive it in a totally new way. The context of the movie combined with the lyrics, or melody, of the tune bring to light aspects that have been previously ignored. This can drastically change the emotional significance of a song, turning one you never cared for into a new obsession.
The music makes the movie
Another way music in movies changes our tastes is when it is used to create an atmosphere. "Donnie Darko" is a classic case: an assortment of popular as well as underground '80s songs helped to create the feeling of being in that decade. With this particular case, the music assists in the whole aesthetic of the picture. Soundtracks can also become as well known as the movie itself. The "Batman Forever" soundtrack is a highly successful album, yet the majority of the tracks do not appear in the film itself. Instead, the diverse collection of songs brought attention to the music artists in addition to the movie.
In all of these cases, the way particular music is presented can drastically change the perception of it. Cheesy love songs that may have flopped initially can transform into meaningful music, serving as reminders of a cherished loved one. Witty covers of old tunes figure prominently in many of today's movies, especially comedies.
When our powers combine
Music is a powerful tool for telling a story. Musicals are still immensely popular, and current musical trends have even influenced them. The most popular Broadway show today is "Hamilton." (In fact, getting tickets is pretty much impossible.) This is a play primarily employing devices used in hip-hop to convey its messages. "Hedwig and the Angry Inch" marries '80s hair metal with the story of a transvestite – something nobody ever expected and lending depth to a genre of music commonly regarded as shallow.