Why pvp is succesful and pve is getting stale

[Valence]

Oh, don't get me wrong - I am right there with you, especially since I have been with the game since 2.0, have seen that it used to be more, and I am lamenting the state it is in now. If your ideas were to come to pass I'd be super happy.
My worry is that the game has had this "Shadowbringers" kinda design for years now, and a sudden change in design paradigms may also alienate players, which is why something like that may have to be established very carefully.

Don't worry I was mostly arguing against an imaginary point of view. Call it a strawman if you will I guess.
I understand the player alienation, but on the other end, I also feel alienated by what they did over time so... There is a point as I said where it's just incompatible mindsets and goals for the game, and I'm not ashamed to say it, especially when it used to be more balanced instead of this encounter extremism we have now. If anything, I'd just like them to dial back a little and reintroduce some of what made XIV more balanced than it currently is, even if it remains mostly scripted to the bone. There are also instance design changes that could frankly introduce variations as well.

PVP is successful???

Yep. Pops almost all day long except in the night.

FFXIV is a game, and a game by definition has a challenge.
If you bypass the challenge cheating or leaving others solve the problems for you, the game lose an important quality/component of being a game. By definition, an activity without a challenge is a work.

Now, I cannot be a "student" forever. Soon or later I'll graduate (better sooner than later) and I leave the univ... the game.
If you don't feel any challenge anymore and you aren't cheating... good job, you are graduated now, but don't expect a game becoming more challenging with every expansion, because there are a lot of "student" and you cannot cut them out from the content.
If you think about it, the new 24 raid is a good thing. "students" can learn and have a challenge, "graduated" can explain and have a challenge leading a cat herd.

As I (implictly) said before: do not cheat, do not search for shortcut, accept n00bs and do not transform a game in a unpaid job.

So we went from blind runs to cheating to bypass the challenge? Why are we even speaking about cheating now?
You're confusing work with lack of challenge, work, at least in the way you seem to bring it forth as tedium, generally comes in opposition to entertainment, not challenge. One can enjoy challenge, but one can also find challenge egregiously tedious. This is just apples and oranges.
If your point about challenge is that people trying to streamline strats or just people not going in blind, are "cheating", well, that sure is a take I guess. A true purist for respecting the content... Good for you.

But as evidenced with the new 24 raid, I'm afraid I really don't share the same observations at all simply because the mechanical systems of the game do not allow much wiggle room for graduates to help students much, which leads to frustrations on both sides mainly tied to speed of progression, and the sheer amount of players driving the probabilities for wiping mistakes to happen dramatically.

I agree with the sentiment of OP, though I fear we might have to hope for a successor game to implement it because I highly doubt they can engineer that kind of change into this one, considering how many years they struggle already on far smaller and simpler things.

My hopes are as high as the landmass of the netherlands.