The Second Vatican Council used very nice words to describe church music in Chapter Six of its Liturgical Constitution.
The musical tradition of the universal Church is a treasure of immeasurable value… Sacred music increases in holiness to the degree that it is intimately linked with liturgical action. This Sacred Council maintains the norms and precepts of ecclesiastical tradition and discipline. Great importance is to be attached to the teaching and practice of music in seminaries… and also in other Catholic institutions and schools. Gregorian chant should be given pride of place in liturgical services. Composers, filled with the Christian spirit, should feel that their vocation is to cultivate sacred music and increase its store of treasures. Let them produce compositions which have the qualities proper to genuine sacred music… The texts intended to be sung … should be drawn chiefly from Holy Writ and from liturgical sources.
The Constitution outlined a view of church music in which Gregorian chant (as most suitable for the liturgy), polyphonic music of artistic quality, and religious hymns of the congregation are balanced with each other and “give a more noble form to the liturgical action”; a church music in harmony with the ecclesiastical traditions having “the spirit of the liturgical action”, “the spirit of the liturgy” as its highest norm; church music under the care of diligent bishops, and priests receiving a solid musical education.
In actual fact, however, church music fell into such a deep crises after the Council as never before in its history. In a great part of the Church over the world, church music is not cultivated but neglected; musical rubbish prevailed; sacred music fell in many places into the hands of uneducated dilettantes; its fate and daily practice depends upon decisions of priests who stand in this matter (too) very far from the true spirit of the Council. The “treasure of immeasurable value” is dissipated; in many churches the most frivolous music resounds without a single word of warning from the hierarchy; and the music which predominates can be called anything but “the expression of true art.”
The responsibility for this decline lies firstly with the ambiguous instructions of the post-conciliar committees, secondly with the church authorities who neglected to fulfill the will of the Council, thirdly with the clergy and in fourth place with the church musicians themselves. Before entering into details, I mention briefly that in my opinion the matter of church music is not a question of music. Good church music exudes into pastoral practice, spirituality, church discipline, morals and even theology. Bad church music likewise affects all this but in a destructive manner. And vice versa: behind the lapse of church music, liturgical lapses lie hidden; behind the liturgical lapses an incorrect image of the Church, and in the last analysis, implicitly heretical views. It ought to have been the task of theologians familiar with church music or church musicians with expertise in theology to express clearly the deeper roots of the theology of worship and of its music in order to expel the suspicion of being cultural aristocrats and defenders of purely aesthetic values.
Laszlo Dobszay, The Bugnini-Liturgy and the Reform of the Reform (2003)