I’m not sure exactly where you are coming from. I know that in Germany they never abandoned the Latin ordinary and typically sing it alternatim, which as you know is a form of responsive singing. In other words, the choir will sing one verse of the Gloria or Credo and the congregation will respond with the next one. (In fact, they do the same thing at St. Peter’s in Rome and therefore I suppose commonly throughout Europe.) To tell you the truth, this annoyed me no end, as I read music very well and know all the peculiarities of German pronunciation of Latin, and wanted to sing the whole thing through. However, it is preferable to many possible alternatives, as I’m sure Cavaille-Coll and others can appreciate.
I hate to be the eternal pessimist, but ordinary (meaning common usage) parish worship in the US is at this point so degenerate that almost anything would be an improvement. It seems almost pointless to pick out one problem over another. I have ventured posts on some of the other forums with limited success, but here I feel that if I make a bald statement like that I may not have universal agreement, but at least considerable sympathy.