SUGGESTION: Turn Bluemage into a regular job - Limited Job>Advanced Job (An Approach)

[ADVSS]

How much is too much? Technically the real answer would be "when it replaces actual tanks/healers, and locks them out of party finders".
But the easiest way to handle it, would be to balance BLU based on its DPS role. After that, any tanking/healing options are intentionally undertuned (not equally balanced with current tanks/healers) This way if you're doing lesser content, the BLU can fill in the role of healer/tank for premades. It could even be possible in easier EX trials, if people are good enough/geared enough to make up the difference. But ideally you want an actual healer/tank job to fill that role, so this is only for desperation, rather than efficiency. (this of course requires a lot of changes to BLU tanking/healing, even DPS honestly)

By doing this, 4man BLU dungeons still function the same way they do now. You have to go in as a premade. But this also allows for normal gameplay. (Im still partial to having BLUs get most of their EXP outside of dungeons, and mostly running dungeons for spells/gear, rather than for good exp. its just nice flavor to this job, plus its faster leveling can make up for the fact it has to hunt down spells, which is where most of the grind actually is.)

To be fair, and i agree with you, but using AM and say mighty guard, is way inferior to a tank using tank stance(75% attack power reduction for 20% defense and increased enmity), as well as am and pom cure/exuviation/gobskin, is nothing compared to a dedicated healer. WW could still be kept and put on a cd timer like angel whisper, and that would immediate shut down BLU chances at overshadowing even RDM at this point(also think WW is a trap spell personally, but eh it has its uses, its just fundamentally a bad spell that cost as much as a raise imo and its best use is when its blatantly overhealing the party). A restrictive raise, and bomb heal, but only before massive raid damage, or after moderate raid damage, isnt really going to step on any roles toes, it just may be slightly more supporty than rdm though, if AM simply just became a stance that gave BLU all 3 abilities, instead of one role one, to replace missing traits other casters, healers otherwise get for those level gaps.

EDIT: So after some thinking, i could see them streamlining useful abilities, as a dedicated dps without too much fuss honestly. They could just have BLU keep its utility skills like gobskin/exuviation, and keep AM as well as giving it all 3 traits as either a stance you turn on/off(boring) or
Give AM the Enochian treatment, maybe have the bigger spells activate upon it being activated, have an easier way of maintaining it in combat, sort of like RDM, but have the combos less randomized/proc based like BLM(ezception being thunder procs) Set the job guage around maintaining AM, but less severe than BLM(if you even call it severe now a days) as the combo spells will be pretty straight forward. Use gauge like RDM for burst spells like shock srtike, etc.