"The New Mass is what Vatican II ordered."
Vatican II, in its Sacrosanctum Concilium, gave sensible guidelines for the reform of the Liturgy. Unfortunately, these guidelines were largely ignored in the decade that followed. RUPTURE!
"All but four of the Council Fathers voted for the New Rite."
No; what all but four of the Fathers voted for was Sacrosanctum Concilium. But this actual Conciliar Decree was largely ignored once 'the Experts' got their hands on the levers of power. RUPTURE!
"Modern Catholic Worship is what the Council wanted."
Even the New Rite as actually drafted after the Council had ended, and as authorised by the post-Conciliar popes is not what you get in most ordinary parish churches. For example: the official New Rite wants the First Eucharistic Prayer, the 'Roman Canon' to be used on Sundays and major feast days. It is largely ignored today. Does anybody seriously think that the Ottavianis and the Lefebvres would have voted nearly unanimously and without complaint for a New Rite in which the Canon of the Mass would be replaced by poorly-conceived committee-manufactured Eucharistic Prayers? RUPTURE!
"Everything, the Liturgy included, needs to be updated. That's why we need the New, modernised, Rite."
Updated? OK, then, let's consider the implications of your claim. It's now more than fifty years since the the New Rite was brought in. Time, therefore, now, according to you, for an even newer one. WE NEED TO RUPTURE OUR WAY AHEAD, TO BOLDLY RUPTURE WHERE NOONE HAS RUPTURED BEFORE!!
"But the New Rite takes account of Modern liturgical thinking."
No it doesn't. It takes account of the thinking of the late 1960s.
"But isn't that recent enough?"
Well, the people who invented the New Rite around 1967 didn't confine themselves to the liturgical thinking of around 1907, so why should we all be stuck with 1967? In Liturgical studies, as in everything else, things move on. Sixty years can be quite a long time in the History of Ideas. You are reading this on a computer ...
"But only a few eccentrics are unhappy with the New Rite."
Really? Joseph Ratzinger? Cardinal Sarah? Competent academics throughout the world?
"So how does the modern thinking of today differ from that of the 1960s?"
Very briefly: in the 1960s, Liturgy was commonly seen as having a primary purpose of enabling the Laity to understand their Faith and Worship better. So everything ... the 'experts' felt ... should be very clear and orderly and precisely expressed. Within the last generation, academic work has taken account of a distinction between 'orality' and 'literacy'. The Liturgy , according to more recent linguistic analysis, is in an 'oral' style in which repetitions and digressions, even stutterings and rebeginnings, are natural. Body-language, hints, allusions and nuances are part of communication which is the Church's act both of union within herself across time and space, and of love towards her Lord. An Anglican scholar called Catherine Pickstock, and a Catholic theologian called Fr Aidan Nichols have written well about such things.
"And you're saying that in the 1960s nobody understood that sort of stuff?"
Well, there was a most distinguished Dutch scholar called Christine Mohrmann, but, poor thing, she was not a member of the highly exclusive Big Boys' Club (CathPop!) of "We are the Elite Liturgical Experts and we know everything". She was cleverer and more learned than the 'Experts', so she was never given a look-in
"So you're saying that every sixty years, the entire Liturgy should be turned upside down."
No, I'm saying the opposite. It is a very bad idea to put the entire liturgical inheritance into a melting pot every generation or two. What the Council actually ordered in Sacrosanctum Concilium (why not read it?) was an organic and evolutionary approach, gently updating and adjusting. Which is what has happened throughout the nearly two millennia of Church History. That was a good policy, human and humane. It is a shame the words of the Council were ignored.
"So where ... in practical terms ... should we go from here?"
At least for the time being, a mixed economy and a gentle tolerance of liturgical diversity seem to me sensible. New Rite in Latin; New Rite in English; Old Rite in Latin; Old Rite in English ... that would be a true policy of leaving things to God, wouldn't it? Look up Gamaliel in Acts 5!