New commenter Tony Phillips mentioned this:
Paul VI had absolutely no right or authority to make massive changes to the liturgy.
On the second point, wrong. Clearly, he had the authority and almost every Catholic bishop endorsed the full program of liturgical reform begun with Vatican II. The specifics were entrusted to others, but Pope Paul signed off on it all. As well as mostly every bishop in the world. And change came. That sounds like a de facto authority to me.
No right.
It is a feature of Westerners, especially Americans I thought, to speak in terms of rights. I’m sometimes suspicious of this. Not because I don’t believe in rights and advocate for them. I think they have a neglected companion in our–rather many–cultures: responsibility.
It may be more accurate to suggest that the Bishop of Rome and other bishops have serious responsibilities where the people of God are concerned. They have responsibilities for the good of the whole Church. That includes changes in the liturgy for the greatest discernible good.
Lacking the right or authority to change the liturgy: this is something more attributed to people in connection with the Bible. The canon of Scripture was mostly set East and West by the 3rd-4th century. At Trent, that was codified for Roman Catholics, but mostly in response to the Reformation dropping diasporan sources of Jewish Scripture.
I don’t think the liturgy qualifies as a canon on this level. The earthly incarnation of liturgy is derived from the Bible. It is not quite on the level of adding things to the Old and New Testament.
I know that a small minority of Catholics were embittered by liturgical reform and they remain so. But having disagreements with lawful changes that were massively accepted by Catholics worldwide isn’t helped by suggesting people had no power or moral standing to change the liturgy.
Catholic Sensibility 
And, unfortunately, once you start down the path of arguing that the changes were made without authority, you’d end up here:
http://www.traditionalmass.org/articles/article.php?id=19
Now, it’s a rather different thing to argue at the prudential level.
And it’s still another thing to revisit prudentially the entire arc of development of pontifical law since the mid-11th century. But it’s a thread that is interwoven into that whole thing. Does the Third Millennium Papacy need to look like the Second Millennium Papacy? Pace the popular history that the 11th century represented a papal power grab, there’s a reasonable historical argument to be made that it was a development *from below* (and is that development fixed in place or subject to further development?). Here’s an overview of a recent somewhat popular-level treatment of that perspective: http://www.praytellblog.com/index.php/2015/02/27/book-review-the-restoration-of-rome-barbarian-popes-and-imperial-pretenders/
I only know of one set of laws which were carved in stone by God.
(Cue for Mel Brooks….)
I didn’t know whether to laugh or cry at Tony Phillips comment which inspired this post. Your response is spot on.
Commenters like Phillips need to read a little more history, be it for example Edward Foley or Keith Peckler’s histories of how the Eucharist has been celebrated down through the centuries. Or on a more general level of Church History, the recently published essay collection of respected Church HIstorian, John W O’Malley, “Catholic History for Today’s Catholics” (Rowman & Littlefield, 2015). Would make a good choice for a reading group.