There have been more and more articles recently on opposition to the Motu Proprio by various bishops. This news is not exactly surprising and I can see why some bishops would be upset by the freeing of the Tridentine Rite.
Pope John Paul II wrote in his Apostolic Letter Ecclesia Dei:
c) moreover, respect must everywhere be shown for the feelings of all those who are attached to the Latin liturgical tradition, by a wide and generous application of the directives already issued some time ago by the Apostolic See for the use of the Roman Missal according to the typical edition of 1962.(9)
So basically the issuance of of Motu Proprio on this subject means that this didn’t happen and the Pope believes that he had to override the lack of response by many bishops. If those priests who wanted to celebrate the Tridentine Rite had received permission from their bishops in the first place this document by the Pope would not have been needed. The Motu Proprio really is an indictment that a "wide and generous application" was in point of fact narrow and stingy.
Regardless though of the history of this issue Fr. Z makes some great points here.
Fr. Z’s 5 Rules of Engagement for When and If the Motu Proprio Comes:
1) Rejoice because our liturgical life has been enriched, not because "we win". Everyone wins when the Church’s life is enriched. This is not a "zero sum game".
2) Do not strut. Let us be gracious to those who have in the past not been gracious in regard to our "legitimate aspirations".
3) Show genuine Christian joy. If you want to attract people to what gives you so much consolation and happiness, be inviting and be joyful. Avoid the sourness some of the more traditional stamp have sadly worn for so long.
4) Be engaged in the whole life of your parishes, especially in works of mercy organized by the same. If you want the whole Church to benefit from the use of the older liturgy, then you who are shaped by the older form of Mass should be of benefit to the whole Church in concrete terms.
5) If the document doesn’t say everything we might hope for, don’t bitch about it like a whiner. Speak less of our rights and what we deserve, or what it ought to have been, as if we were our own little popes, and more about our gratitude, gratitude, gratitude for what God gives us.