Frankly I don’t see this generational divide where I sit (in Quebec). The divide is that the millennials, or their immediate predecessors simply don’t go to Mass, period.
I am a baby boomer (born 1958) and though I love the OF Mass, I don’t love so much how it is executed in parishes in my area. Hence, I have joined a Gregorian schola, and worship in an abbey where the OF Mass is said in Gregorian chant (Latin and some Greek) and French plainchant. No EF Mass close to where I live other than SSPX, which I am allergic to. So the abbey is as traditional as it gets. Oddly enough, Mass is packed there on Sundays. While many are younger folks mostly coming as a side-event to their trip to the gift shop to buy their renowned cheese and cider, who you only see once and never again, there is a hard-core of “good liturgy fanatics” who show up almost every Sunday. Most of whom are baby boomers. I know many Gregorian choristers in our schola and others, and though there are younger members, most are baby boomers.
So I don’t buy the generational thing.
Wait… it only did that in the 1960s.
This is absolutely false. Until Trent, if you worshipped in England you used the Sarum Rite, in France, the Gallican Rite, in Rome, the Old Roman Rite, in Milan, the Ambrosian Rite, in Spain, the Mozarabic Rite, in Portugal the Braga Rite, to name the main ones and there were many other regional rites. The Tridentine Rite only became normative after Trent (so 1500 years of alternate rites, plus some monastic/religious orders), and the OF Mass that we know today came some 407 years after the end of the Council of Trent.
So no, the Mass was not “unchanged” for 2000 years until Vatican II.