It's been 35 years since the USCCB unleashed Music in Catholic Worship on the country. This is the document that said "the musical settings of the past are usually not helpful models for composing truly liturgical pieces today"--so much for the inestimable value of chant--and further said that the distinction between propers and ordinary "is no longer retained."
It proposed an amorphous three-fold judgment of music (pastoral, musical, liturgical) that not only created confusion but strangely left out the theological judgment. Its focus was mainly on the use of music to the congregation ("assist the assembled believers to express and share the gift of faith") not on worshiping God.
For all these years, this document has exercised amazing influence in the lives of American Catholics. Musicians have been sent to conventions, and they are told about MCW and they would come back with the appointed cheers, and proceed to introduce every manner of far-flung innovation in parish music programs, mostly with good intentions. The stories of heartbreak and loss are voluminous.
In any case, next week (Nov 12-15), the USCCB will begin to discuss a completely new draft with a new name. All reports indicate that it is vastly improved, e.g. it actually quotes Vatican II on sacred music. It's been a very sad time in all these years but let us look forward the future.