Many reasons are given why the 1955 missal should be rejected. I’ll point out the facts, certain Catholic teachings along with my opinion and let the reader decide the answer.
1. Pope St. Pius X and Pius XII were calling for and working on reforming the liturgy. Pope St. Pius X began with Divino Afflatu November 1, 1911.
2. The Sacred Congregation of Rites promulgated the explanation for the 1955 reform in a general decree that can be read here.
Whatever the final outcome was to be, the changes would not have led to the 1969 Novus Ordo Mass of Paul VI, but to another mass that was fully orthodox because…
3. Pope Pius XII declared a year after the 1955 reform: “the faithful must seek from Scripture, tradition and the sacred liturgy as from a deep untainted source.” Haurietis Aquas, May 15, 1956.
4. Pope Pius XI declared: “Not least among the blessings which have resulted from the public and legitimate honor paid to the Blessed Virgin and the saints is the perfect and perpetual immunity of the Church from error and heresy.” Quas Primas, 22, Dec. 11, 1925.
5. Pope Gregory XVI declared: “Furthermore, the discipline sanctioned by the Church must never be rejected or branded as contrary to certain principles of the natural law. It must never be called crippled, or imperfect or subject to civil authority. ” Mirari Vos, 9 (1832).
Other papal teaching could be provided including theologians such as…
6. P. Hermann, Institutiones Theologiae Dogmaticae (4th ed., Rome: Della Pace, 1908), vol. 1, p. 258: “The Church is infallible in her general discipline. By the term general discipline is understood the laws and practices which belong to the external ordering of the whole Church. Such things would be those which concern either external worship, such as liturgy and rubrics, or the administration of the sacraments…”
7. McHugh and Callan, Moral Theology wrote: 415. The dangers of epieikeia also place limitations on its use.
(a) There is the danger that one may be wrong in judging that the lawgiver did not wish to include a case under his law. If this is not certain, one should investigate to the best of one’s ability, and have recourse, if possible, to the legislator or his representative for a declaration or dispensation. It is never lawful to use epieikeia without reasonable certainty that the legislator would not wish the law to apply here and now.
(b) There is the danger that one may be in bad faith in deciding that the common good or justice requires the use of epieikeia; the motive in reality may be self-interest or escape from obligation. Hence, a person should not use epieikeia except in necessity, when he is thrown on his own resources and must decide for himself; and, even then, he must be sure that he acts from sincerity and disinterestedness.
In light of the Catholic teaching, can we ascribe to the 1955 reform that it has “false principles and practices” that are found in the 1969 Novus Ordo Mass of Paul VI?
Can we say that using the 1955 reform promotes the dangerous error that Paul VI’s “reform” was merely one more step in the organic development of the Catholic liturgy? If so, then how was the 1955 reform ever really untainted, perfectly and perpetually immune from error, or perfect as the Church declares the liturgy must be?
Is it absolutely necessary to apply epieikeia?
Who decides?
One thing is certain. To claim the 1955 missal was inherently bad (as all the arguments appear to be), then one is rejecting the 2nd article of Faith at least implicitly.
Is it not really the case that the private interpretation for applying epieikeia to the 1955 missal promotes this dangerous heresy anyway?
Speray's Catholicism in a Nutshell 