Some arguments are only convincing to people who already agree with the point being made, and some arguments are convincing to everyone who hears them (even to those who ignore that they have been convinced and suppress the truth in their sin). The latter are those powerful points that the Church has made in her dogmatic statements: the Scriptures, the Creeds, the ex cathedra statements of the Holy Fathers, etc. The former, however, are not always thought through clearly. If one does not believe that his listeners are going to object, he does not need to put much effort into proving his point. The result of this last situation is that sometimes less than wonderful arguments are put forward.
Pope Leo, said recently that the Church was right to "change" the liturgy after Vatican II. Now, thank God, he did not say that all the changes that occurred contrary to the actual rules were in themselves right (but then, usually only heretics and lunatics say things like that). Now, I have to make it clear: I am not an official Church theologian, nor am I a Canon Lawyer, nor do I have a degree in sacred liturgy. Thus, as a simple country priest, I have to say that his explanation was "interesting" to put it mildly. Maybe I am missing something, and I am completely willing to accept correction on this one. Yet, the explanation seems to go something like this: the Church was right to develop the Novus Ordo because it was right.
Read it yourself here.