Particularly in the case of this particular document, misunderstandings still abound. They began immediately after the Council.
In 1966, Pope Paul VI wrote one of the saddest apostolic letters ever written, to the superiors of the clerical orders bound to sing the Office in common, to address a major misunderstanding. Apparently, letters requesting all sorts of indults were flooding the mails, and many of these from those whose observance of the Liturgy should be the vanguard. Not everyone can sing in Latin--but clerics can. Not everyone can learn Gregorian chant--but those who sing daily in choir can.
On pages 121-122 of his book A Pilgrim in a Pilgrim Church, Rembert G. Weakland, OSB, explains how the Council of Abbots of the Benedictine Order--who should have been on vanguard--decided to completely disregard this apostolic letter.
In our day there is some evidence that a new richly observed Liturgy is being practiced more and more in religious houses. But the sad misunderstanding is still all too commonly observed instead. Who are our liturgical leaders, if not the monks?
The Apostolic Letter reads in part:
...What is in question here is not only the retention within the choral office of the Latin language, though it is of course right that this should be eagerly guarded and should certainly not be lightly esteemed. For this language is, within the Latin Church, an abundant well-spring of Christian civilisation and a very rich treasure-trove of devotion. But it is also the seemliness, the beauty and the native strength of these prayers and canticles which is at stake: the choral office itself, ‘the lovely voice of the Church in song’ (Cf. St Augustine’s Confessions, Bk 9, 6). Your founders and teachers, the holy ones who are as it were so many lights within your religious families, have transmitted this to you. The traditions of the elders, your glory throughout long ages, must not be belittled. Indeed, your manner of celebrating the choral office has been one of the chief reasons why these families of yours have lasted so long, and happily increased. It is thus most surprising that under the influence of a sudden agitation, some now think that it should be given up.
In present conditions, what words or melodies could replace the forms of Catholic devotion which you have used until now? You should reflect and carefully consider whether things would not be worse, should this fine inheritance be discarded. It is to be feared that the choral office would turn into a mere bland recitation, suffering from poverty and begetting weariness, as you yourselves would perhaps be the first to experience. One can also wonder whether men would come in such numbers to your churches in quest of the sacred prayer, if its ancient and native tongue, joined to a chant full of grave beauty, resounded no more within your walls. We therefore ask all those to whom it pertains, to ponder what they wish to give up, and not to let that spring run dry from which, until the present, they have themselves drunk deep.
Of course, the Latin language presents some difficulties, and perhaps not inconsiderable ones, for the new recruits to your holy ranks. But such difficulties, as you know, should not be reckoned insuperable. This is especially true for you, who can more easily give yourselves to study, being more set apart from the business and bother of the world. Moreover, those prayers, with their antiquity, their excellence, their noble majesty, will continue to draw to you young men and women, called to the inheritance of our Lord. On the other hand, that choir from which is removed this language of wondrous spiritual power, transcending the boundaries of the nations, and from which is removed this melody proceeding from the inmost sanctuary of the soul, where faith dwells and charity burns – We speak of Gregorian chant – such a choir will be like to a snuffed candle, which gives light no more, no more attracts the eyes and minds of men...Much more here.