On the First Sunday of Advent (November 30), 1969, the New Missal entered into force officially (it would take a few years before it was to be completely phased in worldwide).
In his words in the General Audience which immediately preceded that date, Pope Paul VI was clear:
We may notice that pious persons will be the ones most disturbed, because, having their respectable way of listening to Mass, they will feel distracted from their customary thoughts and forced to follow those of others....Not Latin, but the spoken language, will be the main language of the Mass. To those who know the beauty, the power, the expressive sacrality of Latin, its replacement by the vulgar language is a great sacrifice: we lose the discourse of the Christian centuries, we become almost intruders and desecrators [intrusi e profani] in the literary space of sacred expression, and we will thus lose a great portion of that stupendous and incomparable artistic and spiritual fact that is the Gregorian Chant. We will thus have, indeed, reason for being sad, and almost for feeling lost: with what will we replace this angelic language? It is a sacrifice of inestimable price.
Naturally, elsewhere he mentioned why it was a "necessary" sacrifice, an innovation that was in strict obedience to the Council...
Thank you, dear Lord and most gracious Lady, for Pope Benedict XVI and Summorum Pontificum (after Humanae Vitae, naming Fr. Joseph Ratzinger Archbishop of Munich will one day be seen as one of the most influential and decisive acts of the Montinian pontificate).