Someone recently asked me what the difference is between the modernist pursuit of the "new" and the promises that God "makes all things new". Great question! The "new" thing is not always bad, certainly we would all agree with that. New babies are wonderful! And babies are a perfect example of what the difference is that we need to distinguish. Babies come from the previous generation (even if you try to make life in a laboratory, we do not have the ability [and never will] to create life out of nothing -- we always have to use pre-created matter that God has given us). The "new" that God creates is something that develops from the old.
Modernism always seeks the new at the cost of the old. In the modernistic scheme, new is always better precisely because it is new -- no questions asked. If it is old, then it is wrong and must be rejected (which, in case you were unaware, was the rallying cry of socialism, and communism). In fact, we could go so far as to say that modernism does not just seek to replace the old with the new, it goes a step further and tries (at all costs) to destroy the old (because it fears it). When older people try desperately to hide their age and look like they are still 18, they are rejecting the old and wanting to restore the new, contrary to what God has ordained. When people accept Scripture's statement that old age is a blessing, and that children are the glory of old age, they properly accept that new is supposed to flow from the old.
This is not, of course, to say that the old is always better than the new. Even Scripture points out that the New Covenant is "better by far" than the Old Covenant. Yet, what is the relationship between these two? The New does not hate the Old, rather it grows (somewhat organically) from the Old and is the natural improvement of it; similar to the child coming from the parents with the desire that he will take what the parents have given him and use it to come even closer to God.
In the Catholic understanding of the new, it always flows, in some way, from the old. The tree comes from the seed which came from a previous tree; child from parent; resurrected body from fallen body; new heavens and new earth from old fallen heavens and earth, etc. The new in the work of God is always for the sake of developing the old into something better, but is never a complete rejection of the old. We find the truth that the "new covenant is hidden in the old, and the old covenant is revealed in the new". One flows from the other. In fact, we could say that the way that God always brings in the new is in support of the old. The new child is to honor parents and hand on what they handed on to him to a subsequent generation. This is antithetical to modernism. For modernists, the child must reject and disrespect the parents; they are a hindrance to what is "new" precisely because they are "old".
In this way, Catholicism would say that the new is never automatically better; it is only better if it truly does remain connected to the original old, and grows properly from it. At the same time, the old is never automatically better (although it may seem that we think that way to some modern clergy who are terrified of anything older than 1965!); old is only better when the new is a perversion and/or rejection of the old. Modernism seeks to change our bodies to make men into women, and people into machines. God seeks to change our bodies to make them eternal in the resurrection. These are two entirely different philosophies.
Thus, let us apply this idea to liturgy. The Mass always must flow from a previous form of the Mass, and they all must go back to the Apostles. If something is truly new and has no true "parent" in the liturgical line, then we would see that is based in modernism and its promoters would thus have a strong distaste and rejection of what was old. They would treat it as "the old way" as though that always makes it bad (though no one does that today, do they?!). When a priest chooses to innovate in the Mass, he is moving towards doing something truly "new" (since the Church has never approved innovations in the Mass). When a priest follows the rules of the Mass (1962 Latin Mass or Divine Worship) he is obeying a new rule that flows directly from the old rules of the past.
God works to make things new when the old is fallen and incomplete. The world works to make things new because it cannot accept the old. It does this because ultimately it wants to cast off the authority of God. God gives us what is new because He loves what is old and brings the old to maturity in the new which He loves even more.