This post by Father Longenecker is a worthy read for church musicians and singers. His key point is this:
Finally, it seems to me that the underlying problem with the contemporary hymns is an almost universal lack of understanding in the modern American Catholic Church about what Mass is in the first place. If it is a gathering of friendly Christian people around the table of fellowship in order to get strength and encouragement from one another as we all think about Jesus, why then the contemporary hymns fit the bill very nicely, but then, so would quite a few snippets of music I can think of like--"My favorite things" from The Sound of Music.
However, if the Mass is meant to take us to the threshold of heaven; if it is meant to be a glimpse of glory and a participation in the worship of the spheres of heaven itself, why then the sentimental, sweet and comforting songs just won't do. They wont' do not because they are bad or untrue, but because they are not good and true enough. Worship that takes us to the threshold of glory needs to be, well...glorious
This is, I believe, the key problem. We need to remember what the Mass is, and why we are there.