I've been singing in church since I could sing. I've been a member of too many choirs to mention, and credit the church for teaching me a life long love of music. I think it is an integral part of a worship service. But lately I have come down out of the choir loft and realized something as a regular congregant. People aren't singing in church any more! Why is that? Here is an article that seems to know why.
It makes the case if a church is in too much of a hurry to modernize; it can leave the congregation behind as their musical abilities are limited to the familiar. It also makes the case we live in a society where congregations want to be dazzled; so worship services have become more and more stage productions that make congregants feel it is not their place to sing. I can surly see that too.
Worship services are just like radio. Play the hits or no one will play with you. "It's got a good beat and you can dance to it", was the number one critique of new music on American Bandstand. "It's familiar and you can sing to it", should be the litmus test for church music.