See Jeffrey Tucker's article at the New Liturgical Movement... here is a short excerpt:
"The very clear motive for doing chant is plain as can be: musicians should seek to do what the Church is now asking of us, and always has. Chant is the music of the Catholic Church. It bears all three marks of what the Church calls sacred: holy, beautiful, and universal. It grew up with the Mass and is bound up with it in every way. "