A comment I have heard expressed by a couple of priests, priests who are as open to the older form of the Roman liturgy as they are to the modern Roman liturgy, is that they have noted their confusion at seeing certain brother priests who are now learning and celebrating the usus antiquior who hadn’t really been actively pursuing the reform of the reform in their modern rite liturgies; they perhaps had not even expressed interest in such.
Of course, there question is simply, why is this?
There are a few possible explanations.
One might be that that, to date, the usus antiqior, like the Byzantine Divine Liturgy (for example) has not experienced the interpolations that have occured within the modern Roman liturgy. As such, it might seem like a reasonable place for priests to express their traditional liturgical interests.
A second reason may be tied to the fact that the reform of the reform is yet crystallizing. As such, many priests, just as many laity, may as yet be uncertain as to what it entails, or how to even begin. They may be uncertain as to what they are even allowed to pursue in the here and now; this can relate to simple questions like the liceity of ad orientem, the use of Latin and so on. Experience would suggest this is an issue -- and also suggest it is something that needs to be more aggressively addressed.
Another possibility is that some priests may strategically see the usus antiquior as precisely a way to begin pursuing the reform of the reform, and so they have chosen to focus their efforts there. Still others may simply find themselves particularly attracted to offering the ancient Roman liturgy in its own right.
However, there is yet another possibility that may exist and it is one which all -- traditionalists, re-reformists and ars celebrandists -- need to vigilant about and steadfastly fight against for it is ultimately tied to a fundamentally problematic view of liturgical tradition itself.
The Potential Problem of Balkanization
A more disconcerting possibility is that some may also have come to believe that the modern liturgical books are for modern liturgical expressions, while the ancient liturgical books are the preserve of traditional liturgical expressions. In other words, that those who want traditional liturgics should not expect them within the modern liturgical form, but look to the ancient liturgical form. Certainly in some of the diocesan responses to Summorum Pontificum one got such a sense at times.
What such an idea effectively does is promote a balkanized view of the sacred liturgy, and one that is quite incorrect.
Catholic liturgical tradition should not be understood as merely "one option" amongst others; that if you want Catholic liturgical tradition you go Parish X or Mass A, but if you don't want that then you go to Parish Y or Mass B. No, it is rather something that should characterize all celebrations of the sacred liturgy.
Understanding this is predicated upon a proper and fuller understanding of liturgical tradition itself. On the one hand, liturgical tradition is not entirely static, so it does allow for development and some variances -- i.e. not all liturgical music must be Gregorian chant even though that is the music that the Church has declared to be particularly suited to the Roman liturgy and to be given pride of place within it. At the same time, this allowance for development is not arbitrarily innovationist, nor is it intended to replace or exclude the traditional forms. Those variances and developments are organic and related back to the tradition, and indeed, to the very spirit of the liturgy itself. Those developments are not arbitrary, nor are they radically subjective or self-determined; they are rather very much tied to the tradition itself --and as I say, should not be seen as replacing or excluding the tradition. If Gregorian chant is to have pride of place, then it means just that, even if it does not mean that one may only have Gregorian chant.
It is in this regard then that I say it is highly problematic if one were to make a divide that sees the modern Roman liturgy as the venue for "modern expressions" and the ancient Roman liturgy as the venue for "traditional expressions". This sort of divide cannot be permitted because all forms of the sacred liturgy, regardless of the liturgical books used or of the particular spirituality of those in attendance, must be traditional in the truest and fullest sense of the word, expressing continuity with the liturgical tradition by not excluding the traditional forms themselves, and, if desired, employing forms that have developed upon that tradition in an organic way that is consonant with the mind of the Church and in conformity with liturgical law.
Evidently the ancient use is important as a living expression of the tradition, but this fact is just one of the reasons why the reform of the reform is also so very important. As a movement it works against this idea of balkanization in the modern liturgy. It brings to the table a statement about the objectivity of the liturgical tradition and its relation to the modern Roman missal: that here too belongs ad orientem, liturgical Latin and traditional forms of sacred music and liturgical art. It further seeks to not only make the statement, but also to enact it within the liturgy.
Let us all be ever more vigilant in resisting any sense of balkanizing of the liturgical forms.