It maybe says something profound about the nature and universality of music vs the relative recency of movies as an art form. Music can be understood and enjoyed more universally. We can listen to music in languages we don’t know and thing it’s great. We can rarely watch a movie without any cultural context and enjoy it. Also movies as an art form have had to evolve fast over their short life, but music has existed for millennia. As a result perhaps old movies age out much quicker because movies need context but music can transcend time and context more easily.