The Tridentine reform did not aim at creating a new, up-to-date liturgy. All it wanted to achieve was to prune off the wild shoots of the late Middle Ages, of humanism and Reformation. It meant to be a reform in the original sense of the word: the restoration of the “pure” forms of the Roman rite. The Trident rite is therefore a special form compared to the liturgy of Paris, Cologne, Prague or to that of the Dominicans, Premonstratensians. The Tridentine reform slightly impoverished the Roman liturgy and mutilated its integrity by disregarding these traditions. (It must be acknowledged, however, that it happened in spite of the original intentions since the norm of Trent was established to replace the 16th-century “modern” reform liturgies, and not the traditions having survived “from time immemorial.”)
These drawbacks, nevertheless, can only be discovered if we compare the Tridentinum with eminent representatives of the Roman liturgy. Compared with other rites outside the sphere of the Roman liturgy or with the Bugnini liturgy, the Tridentinum proves to be a member of the Roman liturgy. In this respect the Tridentine rite is identical with the centuries-old Roman liturgy, being one of its branches itself, while the Bugnini liturgy does not belong to the great family of the Roman liturgy.
In my opinion this distinction was neglected by no means innocently or by negligence. It was done with a purposeful manipulation. The reason why the Bugnini liturgy was introduced as if it differed not from the Roman tradition, but only from the Tridentine rite was to create the misleading impression that all we had to depart from was a 400-year-old “Baroque” tradition. In fact, viewed in the light of the essence of the liturgy, breaking with the Tridentine rite entailed a break with the entire Roman tradition up to that point. If the Roman liturgy is identical with the liturgical order documented from the earliest sources up to the year of 1970, then the Tridentine rite is definitely a member of this tradition, while the Bugnini liturgy is not.
Laszlo Dobszay, The Bugnini-Liturgy and the Reform of the Reform (2003)