Our friends at Rorate helpfully posted the following. Pope Benedict XVI spoke to the French bishops on 14 September, which coincidentally the 1st anniversary of Summorum Pontificum coming into force.
Let us have a look at the pertinent text with my emphases and comments.
Here is a thought to carry with you as you start to read: I have maintained ever since the text of the Motu Proprio was issued that Summorum Pontificum is especially a gift to priests. Part of the Pope’s plan to revitalize the Church’s identity must revolve around her worship… and her priests. Learning the older Mass today changes priests. Priests change their flocks. Flocks change the world around them.
It is never too often said that the priesthood is indispensable to the Church, in the very own interest of the lay faithful. Priests are a gift from God to the Church. Priests must never delegate to the faithful [those] functions which are related to their own mission. Dear Brothers in the episcopacy, I ask you to remain desirous to help your priests live in intimate union with Christ. Their spiritual life is the foundation of their apostolic life. You shall exhort them gently to daily prayer and to a dignified celebration of the Sacraments, particularly of the Eucharist and of Reconciliation, as Saint Francis de Sales did with his priests. Every priest should be able to feel glad to serve the Church. [Don't be a stumbling block to priests.] At the school of the Curé d’Ars, son of your land and patron of all priests of the world, do not cease to repeat that a man can do no greater deed than to give the Body and the Blood of Christ to the faithful, and to forgive sins. …
[Watch this transition... from priesthood to...]
Liturgical worship is the supreme expression of priestly and episcopal life, and also of catechetical teaching. [Note the connection with doctrine. There is a reciprocal relationship between what we believe and how we pray.] Your mission of sanctification of the faithful people, dear Brothers, is indispensable for the growth of the Church. I was prompted to detail, in the Motu proprio Summorum Pontificum, the conditions for the accomplishment of this mission, [the Pope closely links the use of the old Mass with the missionl of sanctification!] in that which relates to the possibility of using both the missal of Blessed John XXIII (1962) and that of Pope Paul VI (1970). [In this statement it sounds like the two Missals are on equal standing. And he is speaking of all priests, not some priests.] The fruits of these new dispositions have already seen [the light of] day, and I hope that the indispensable pacification of the spirits is being accomplished, thank God. [The word "pacification" suggests the desired effect of reunification with separated groups and also a calming and healing of those who have been hurt for so long.]
I comprehend your difficulties, [This is probably a reference to how some more traditional groups are also associated with certain political tendencies.] but I do not doubt that you will be able to reach, within reasonable time, solutions which are satisfactory to all, so that the seamless robe of Christ is not torn anymore. [Again the reference to reunification and preventing groups from splitting away from the Churc.] No one is excessive within the Church. [This is perhaps both prescriptive and descriptive. The idea here is that the Church is very large, capable of sheltering people of many points of view and aspirations.] Everyone, without exception, must be able to feel at home, and never rejected. [This is huge: The Pope is telling the French bishops to stop their relentless stinginess in regard to the more traditional Catholics in France. Alas, for far too long traditional Catholics - and among them especially priests - have been treated with great injustice - and not just in France!] God, who loves all men and wills that no one be lost, entrusts us with this mission of Pastors, making us Shepherds of His sheep. We can only give Him thanks for the honor and the confidence He places upon us. Let us endeavor to always be servants of unity.
Meeting with the Cardinals and Bishops of France,
Hémicycle «Saint Bernadette», Lourdes
September 14, 2008
"Everyone, without exception, must be able to feel at home, and never rejected."
This is not carte blanche to think or do as you please and that, just because you choose to do it, bishops and priests have to accept it.
There is still the rule of law. The rubrics still apply. The Rule of Faith is still our guide.
The Pope said this to, and note these terms, French bishops on Summorum Pontificum and priests.