There were many reasons for Summorum Pontificum, the motu proprio document by Benedict XVI that gave back full rights of citizenship to the Traditional Liturgies of the Latin Church in our age.
Justice, for one. The then-Cardinal Ratzinger had written extensively on the mistakes of the Pauline liturgical reform. But also, and very importantly, the situation of the Society of Saint Pius X (SSPX).
The SSPX had long defended the full freedom of the Traditional Mass as one of its conditions for a final settlement with the Apostolic See. Then, Benedict XVI accomplished the other condition: the lifting of the excommunications of the four SSPX bishops consecrated by Abp. Marcel Lefebvre in 1988; and the German response to the lifting of one of them (that of Bp. Richard Williamson) created one of the gravest storms of the Ratzinger Pontificate. The reaction gave rise to one of the most traumatic writings ever composed by a Pontiff in the modern age:




