This is literally asking for a mage that has ANY skill then and not BLU. It's quite literally teh point I made earlier about BLU being a reskinned caster. That youre not asking for blue mage, your asking for a caster named blue mage. Thats fine if thats what you want. But it's not a BLU mage in regards to theme if none of the facets of what makes a blue mage a blue mage exist. In this specific case, its learning MONSTER SKILLS. Not any skill. Monster Skills.
You have literally zero idea if its going to be a garbage fire, DoA or anything. How do I know this? Cause youve not played it. No one has. Its your own personal outrage and bias speaking to this and in that regards, is absolutely meaningless.
As for identity, identity is what people are ASKING for. People want BLUE MAGE, not just a caster. Theyre asking for a specific thing, with a specific identity. The identity here is a caster who uses monster skills learned from monsters. Thats the crux of it. What you said above in regards to "I dont care what it looks like, so long as it does numbers" is a complete antithesis to what people were asking for.
Not to be flippant, but I stated some of this. People broadly agree that the skills would have to be nerfed if they were in party play. The disconnect is how the nerfing of the skills affects teh overall playstyle of identity of what BLU is. It boils down simply to this: As long as the skill is named bad breath, that is fine. Youre using the "monster skill." Even if it's not really teh same skill, and if the class is going to have a playstyle similar to other classes thatll probably revolve around resource management in some regards. Even if learning skills from monsters is a throw-away gimmick for learning these spells-in-name-only, that is all fine. That most skills you get will only be DPS orientated because defensive and support based skills will be limited as to not upset the Trinity. All that is fine, so long as its called BLUE MAGE.
This boggles the brain a bit for me, because after all those concessions, it feels like people are just more concerned with having caster named blue mage, then they are with playing Blue Mage as a class.
So a few things to consider: In ff7 there were items that prevented status effects. It wouldnt be strange for bosses to also have immunities. Second, youre comparing a single player game vs a multiplayer one. If FFXIV was single player, BLU wouldnt matter if it was OP status broadly. However, its not. So you have to consider skill balances in regards to things like raid content or any party play content. Before you get out over your skis on what I just said, the consideration here being made is that immunities on bosses wouldnt rule out a skill being closer to 'true to spec'. PCs arent bosses, so what immunities we would have would be limited in comparison to boss monsters.
Remember, bosses are designed to fight 1v8. Imagine how quickly a boss could go down if one of the monster skills was a tank buster? Or how easy bosses that have Add phases would be if you could obliterate them with monsters who have hard hitting AoEs? I mean you could mitigate against that by restricting skills, but that would be ridiculous in of itself. You could do it by mitigating power and range, but then the skill becomes a reskin of another caster's skill which then raises the issue of why bring a blue if they dont bring anything to the table that a BLM couldnt do on top of BLU just being more difficult to get your skills for. In fact, what then sets BLU apart from other casters other than a more contrived way to get your skills. Again, fi thats what you want, fine. Ask for that. But it wouldnt be thematically in line with the identity of what makes a BLU a BLU.
This, of course, doesnt address many of the other issues that would crop up such as the order you learn skills, how to differentiate blues who have skills vs those who dont in party play, and so forth. All those side issues that come up with a system where you can learn skills in any order and at any time. And I know there are plenty of suggestions how to 'balance' that. But with every balance change, the identity of what people were asking for gets mitigated more and more. Until youre left with what I said earlier - a caster whos called a blue mage, and not a blue mage as the lore pushes out.