When speaking of the Tridentine rite, we have to avoid, in my opinion, two misleading views. The Tridentine rite cannot be recommended as the only way to return to the authentic Roman liturgy. The Roman rite was rich in different traditions, and they all represented the same “Roman” rite. So Rome is not equal with Trident.
But, on the other hand, Trident was not something basically different from the traditional Roman liturgy, it was not a 16th-century innovation. The Tridentine liturgy was identical in all essential elements with the Roman tradition – already a 1000 or more years old at the emergence of the Tridentine rite.
The first error is much less harmful, but both come from the same misinformation or (in the second case) a purposeful and tendentious falsification. The Tridentine Breviary was not declared obligatory: the local rites representing at least 200 years of tradition could be maintained in the future. In spite of this “right of long-standing tradition” they were abandoned almost everywhere, and the Tridentine Office gained universal acceptance.
The wave of reforms finally abated and only unessential changes were introduced during the subsequent three centuries. Nevertheless, the “rationalistic” reform-endeavors did not cease in the period. In France almost each diocese had its own Neo-Gallican Office, though their destructive influence (severely attacked 150 years ago by Dom Prosper Gueranger) remained confined to a narrow sphere.
Laszlo Dobszay, The Bugnini-Liturgy and the Reform of the Reform (2003)