Though not necessary for consecration, it does help the faithful understand theologically what is happening.

108. Many of the faithful are unable to use the Roman missal even though it is written in the vernacular; nor are all capable of understanding correctly the liturgical rites and formulas. So varied and diverse are men's talents and characters that it is impossible for all to be moved and attracted to the same extent by community prayers, hymns and liturgical services. Moreover, the needs and inclinations of all are not the same, nor are they always constant in the same individual. Who, then, would say, on account of such a prejudice, that all these Christians cannot participate in the Mass nor share its fruits? On the contrary, they can adopt some other method which proves easier for certain people; for instance, they can lovingly meditate on the mysteries of Jesus Christ or perform other exercises of piety or recite prayers which, though they differ from the sacred rites, are still essentially in harmony with them.

32. If the private and interior devotion of individuals were to neglect the august sacrifice of the altar and the sacraments, and to withdraw them from the stream of vital energy that flows from Head to members, it would indeed be sterile, and deserve to be condemned. But when devotional exercises, and pious practices in general, not strictly connected with the sacred liturgy, confine themselves to merely human acts, with the express purpose of directing these latter to the Father in heaven, of rousing people to repentance and holy fear of God, of weaning them from the seductions of the world and its vice, and leading them back to the difficult path of perfection, then certainly such practices are not only highly praiseworthy but absolutely indispensable, because they expose the dangers threatening the spiritual life; because they promote the acquisition of virtue; and because they increase the fervor and generosity with which we are bound to dedicate all that we are and all that we have to the service of Jesus Christ. Genuine and real piety, which the Angelic Doctor calls "devotion," and which is the principal act of the virtue of religion -- that act which correctly relates and fitly directs men to God; and by which they freely and spontaneously give themselves to the worship of God in its fullest sense[33] -- piety of this authentic sort needs meditation on the supernatural realities and spiritual exercises, if it is to be nurtured, stimulated and sustained, and if it is to prompt us to lead a more perfect life. For the Christian religion, practiced as it should be, demands that the will especially be consecrated to God and exert its influence on all the other spiritual faculties. But every act of the will presupposes an act of the intelligence, and before one can express the desire and the intention of offering oneself in sacrifice to the eternal Godhead, a knowledge of the facts and truths which make religion a duty is altogether necessary. One must first know, for instance, man's last end and the supremacy of the Divine Majesty; after that, our common duty of submission to our Creator; and, finally, the inexhaustible treasures of love with which God yearns to enrich us, as well as the necessity of supernatural grace for the achievement of our destiny, and that special path marked out for us by divine Providence in virtue of the fact that we have been united, one and all, like members of a body, to Jesus Christ the Head. But further, since our hearts, disturbed as they are at times by the lower appetites, do not always respond to motives of love, it is also extremely helpful to let consideration and contemplation of the justice of God provoke us on occasion to salutary fear, and guide us thence to Christian humility, repentance and amendment.

It has also been historically documented that many of the things that the Council implemented were condemned by previous popes and councils. See "Auctorem Fidei," and "Lamentabili Sane."

the Veni Sanctificatur in the EF offertory prayers?