Yes, I think that music in the Middle Ages played an important role in churches, because churches were so important to people in the Middle Ages. In the Middle Ages, other than religion, people did not have much else to cling to. Music was a central part of these religious ceremonies.
I am sure people had a hard time finding entertainment value back in those days. Music in the church had to play a major role in people's life. It probably also helped keep many people believing in the church and religion. It probably was a time that Churches thrived better than anytime ever in history.
Music in the middle Ages played a huge role in churches. The organ being one of the most popular instruments of the time, was played heavily in church then and today. It influenced the music that is being played in churches even to this day, without it church would likely be a very different thing. Music has an important role in many things.
During the Middle Ages, music was one of the biggest aspects of Church, much like it is today in Southern Baptist churches in the United States. And the music of the churches during that time is hauntingly beautiful. If you haven't heard it, I suggest that you find some soon.
While I think that music was greatly used in churches during the Middle Ages, I do not think they were vital to the way the churches were ran. I think that the churches operated without the help of music during that time. I think music was more important for other matters in society.