Obviously there’s a lot more to say, but I think the key to Pope Francis’s decision to abrogate “Summorum Pontificum,” Benedict’s document that liberalized the use of the extraordinary form of the Roman Rite, in the motu proprio “Traditionis Custodes” is that Pope Benedict XVI’s decision failed spectacularly in doing what it set out to do: foster unity. Now Pope Francis intends to work towards unity in the Church, with one, unified Rite in the Latin Church. He makes clear in his accompanying letter that the reformed rite is the unique expression of the liturgy in the Church. The past 13 years have demonstrated that the reformed Rite is essentially connected to the Vatican II, and that further promoting the pre-conciliar liturgy will foster division and hinder the implementation of the Council.
“Responding to your requests, I take the firm decision to abrogate all the norms, instructions, permissions and customs that precede the present Motu proprio, and declare that the liturgical books promulgated by the saintly Pontiffs Paul VI and John Paul II, in conformity with the decrees of Vatican Council II, constitute the unique expression of the lex orandi of the Roman Rite. I take comfort in this decision from the fact that, after the Council of Trent, St. Pius V also abrogated all the rites that could not claim a proven antiquity, establishing for the whole Latin Church a single Missale Romanum. For four centuries this Missale Romanum, promulgated by St. Pius V was thus the principal expression of the lex orandi of the Roman Rite, and functioned to maintain the unity of the Church. Without denying the dignity and grandeur of this Rite, the Bishops gathered in ecumenical council asked that it be reformed; their intention was that ‘the faithful would not assist as strangers and silent spectators in the mystery of faith, but, with a full understanding of the rites and prayers, would participate in the sacred action consciously, piously, and actively.’ St. Paul VI, recalling that the work of adaptation of the Roman Missal had already been initiated by Pius XII, declared that the revision of the Roman Missal, carried out in the light of ancient liturgical sources, had the goal of permitting the Church to raise up, in the variety of languages, ‘a single and identical prayer,’ that expressed her unity. This unity I intend to re-establish throughout the Church of the Roman Rite.”
— from the letter of the Holy Father Francis
To the bishops of the whole world,
That accompanies the Apostolic Letter Motu Proprio Data