<<I think it’s fair to say that the Gregorian Rite is a much more full and much more precise expression of the Catholic Faith than is the Pauline Rite.>>
I think it’s UNfair to say this.
ALL approved rites of the Church are EQUALLY precise expressions of the Catholic Faith.
One has only to put, say, Eucharistic Prayer #4 side by side with the Roman Canon, or the traditional Offertory with the almost non-existent alternate that was put in its place, or almost any of the Propers to see what I mean. I have to run to work right now (I’m on China time

), but we could start a new thread on this topic if it was deemed worthwhile to look at specific examples.
Also, I think you’re not correct about the priest saying Mass by himself. This happens all the time, as a matter of course, no special permission necessary.