I understand your stance but I think you are misunderstanding SE's reasoning for reducing the length of the MSQ.
They are not trying to keep the overall length of MSQ from 1 to 80 at some arbitrary maximum where to put more MSQ in, they need to shorten it somewhere else. They are shortening a specific and notoriously dull section of the MSQ to be more enjoyable.
Adding more MSQ in 5.5 and beyond does not "undo" the fact that post-ARR MSQ is now shorter than it used to be.
Perhaps the problem is that you seem to be viewing the story as some monolithic lump of an obstacle to reaching the endgame and all that matters is the length of it, which simply isn't the case. It is a serialised, chaptered story and there will always be more chapters being added to it. It isn't designed to be kept at a fixed length.
The thing is, making the story "shorter and more digestable" by cutting bits out of it is potentially detrimental to what makes it enjoyable in the first place - especially if you're talking about cutting out entire chunks of the narrative and discarding them as unimportant.
And no, I don't think that it's more important for "everyone" to enjoy it in a shortened format than that the people who like it in its current format can continue to see the whole thing. If I don't like a game or story, I just don't play or watch it, and leave it to be enjoyed by the people who do.
I've written before that there are definitely places in which the overall playtime of the expansions could be tightened up by removing busywork tasks or moving them to sidequests, but I don't think that the answer is taking away parts of the story to appease people who didn't like the story in the first place. Even the apparently-necessary changes to ARR have pulled out at least one part of the story I actually liked - while I haven't played the whole thing to see what's been done, I've heard that the lead-up to Ramuh (with the sylphs playing pranks and transforming into copies of the Scions) has been glossed over with a sentence or two of dialogue. That part was funny, especially if you took the time to speak to the characters between objectives, and now it's just gone.