It comes up frequently on other community forums and am rather surprised it hasn't been posted on the official forums.
In my LS and gameplay I frequently see people abandoning jobs they loved and played for many years to play BLU instead. The reasons for this are multiple, but in my view this isn't much different than when SAM were played so much and 1 hand jobs were given a boost, then too many THF were played and THF was nerfed and then too many people played BST and beast was nerfed. The balance needs restored again or the majority of players in the game might end up playing BLU as one of their active jobs, and that isn't very balanced at all especially considering most people can have time to gear and maintain 3 jobs to endgame levels at most. If this isn't enough proof, look at the number of almaces being made at a sickening rate.
I see its problems as these four points:
1) It has huge aoe nukes, even better than dedicated nuking jobs like BLM. One reason BST was nerfed was it could farm experience points and job points so well, solo. Well, BLU can do this and much more.
2) It has huge soloing potential. I feel one reason BST was nerfed was it could do solo VD battlefields. They can clear those with lots of temps, 1 hours, and high degrees of skill and still take over 10 minutes. BLU is soloing some VD fights in much less time.
3) It can self haste cap, and needs less buffs. The director in the reddit AMA said they didn't want any job to be able to self haste cap as a DD as it is a group game, yet BLU can.
4) It is extremely survivable while also doing great DPS, there is very little tradeoff.
I think this could be solved in a multitude of ways, but am sure SE is able to think of many ways themselves this could be solved. Here are some suggestions I do not expect to be implemented but hope the ideas can help:
A) Nerf their AoE damage. A BLU shouldn't aoe for more than a BLM, let alone have status effects that go on with it that completely disables the entire crowd giving almost no risk even if you don't one shot them.
B) Make them choose more between damage and survivability rather than having both at the same time. This could be accomplished with changes to things like barrier tusk, occultation, cocoon and other defensive spells or by increasing the point costs on extremely good defensive or offensive spells to make them have to choose their role more carefully rather than just be very good at everything. It also means BLU can just go all out and not worry about getting hate from the tank. In fact many setups won't even use a tank they just let BLU do it, and not even change their loaded spells to be more defensive at the cost of damage.
C) Remove haste from MG, the biggest reason to require GEO or BRD in a party is hastecap for DD. As was stated in the AMA, this is a group game. This will also limit their solo potential some as they will be more limited in trusts as every other DD is.
D) Compare their damage output to their versatility and utility, if a change in damage is needed then do it. Though it should be noted that the main draw of BLU isn't that it is the strongest DPS, it's that it is so good of DPS while the rest of this is true and that for the most part due to survival it is rather foolproof and easy to accomplish.
I apologize in advance for posting a topic that will likely require moderation due to flaring passions and people throwing insults around especially by BLU players who enjoy the benefits of the job and do not wish for a nerf, at the same time I feel this is a big issue in the game currently and feel it needs to be posted, the game itself suffers if there is a huge job imbalance and there most definitely is at all levels of play. I think there is a lack of challenging content in the game vs the overall content of the game, and feel it is a lot more work to buff a ton of jobs rather than nerf the one causing the problem. Nerfs do make some of the player base upset, but so does a game where balance problems are left unchecked. I'm sure some BST, THF and SAM quit as a result of changes, but at the same time I doubt it was many and for that same reason only. A new bandwagon job may eventually emerge, but that doesn't mean balance shouldn't be actively maintained. This issue is brought up time and time again on community websites because it is a very obvious issue to players and cause for concern.