Indiscriminate and fawning imitation of the past is bad, according to what we’ve read in Mediator Dei, but research to the early expressions of liturgy are lauded for a source of deeper understanding for the present day. One might ask: is this all?
62. Assuredly it is a wise and most laudable thing to return in spirit and affection to the sources of the sacred liturgy. For research in this field of study, by tracing it back to its origins, contributes valuable assistance towards a more thorough and careful investigation of the significance of feast-days, and of the meaning of the texts and sacred ceremonies employed on their occasion. But it is neither wise nor laudable to reduce everything to antiquity by every possible device. Thus, to cite some instances, one would be straying from the straight path were (one) to wish the altar restored to its primitive tableform; were (one) to want black excluded as a color for the liturgical vestments; were (one) to forbid the use of sacred images and statues in Churches; were (one) to order the crucifix so designed that the divine Redeemer’s body shows no trace of His cruel sufferings; and lastly were (one) to disdain and reject polyphonic music or singing in parts, even where it conforms to regulations issued by the Holy See.
These examples were all in evidence in earlier eras of Christianity, even the Last Supper itself, in many of these examples. Some of these examples are closer to the heart of liturgy than others. And some have been more along the lines of post-conciliar reforms than others.