Hear me out,
I think Limit Break being a shared ability is actually a negative trait.
1.) People often don't know when to use it outside of boss fights. A group of enemies could be pounding on the tank and sometimes a ranged DPS won't think to use the LB to speed up the grind to kill that double pull stack of enemies.
2.) There are times during a raid or trial where a melee DPS will spend the LB right before a difficult mechanic simply because it was at level 3, and half of the party of new to the trial/raid players die, and the healer(s) now have to quickly try and raise half the party while maintaining the tanks and healing the party and DPS when possible, some with fewer resources to keep their mp high enough to manage all 3 things.
3.) sometimes you want to use the level 3 Limit to see your job's animation or to feel special but someone beats you to the punch.
Whatever the reason, having the limit break tied to everyone means someone else can't use it if they need to or want to. I've heard in Crystal whatever, people can use specialized job Limit Breaks, and that sounds cool, maybe we can get something more like that in normal dungeons, raids, and trials as well. I don't know how we'd balance this. Maybe Limits would do less damage across the board, and tanks wouldn't need lv 3 bars for their best shielding limit break, maybe it'd be lv 2. Maybe lv 2 would be the max for everyone, and a party limit break would or could be reserved for situations when its especially needed or something.
Basically, I'm saying maybe a rework for Limit Breaks should be considered. Where everyone can build up to a personal lv 2 limit breaker gauge for their own use.
Healer: Level 1 standard universal group heal spell that's stronger than any jobs group heal. Level 2, a single target Quickcasting Raise/Resurrection Spell, might be usual when your quick cast is on cooldown but you need to raise a 2nd person fast.
Tank: Level 1: A Self-protection spell, Shielding, or Damage negating buff that lasts for a few seconds. Useful if you've already spent your jobs Hallowed Ground or Living Dead but need something like it for another upcoming mechanic. Level 2: A Party shielding ability similar to level 3 but maybe not as powerful or Maybe it's a job-specific damaging LB, the fact that you have to build to level 2 to use it means you're not stepping on the DPS's role.
DPSL These I don't see needing much renovation just allow each DPS to build and use the normal DPS limit breaks they use personally.
Lv 3's could be left the same or maybe depowered a slight bit since at least 2 roles can now DPS a bit with their limit breaks being personal but overall are left for the really emergency based stuff, like a Tank needing to shield the party from certain death, or the healer needing to raise the entire party, or if the boss is down to 6% health a DPS can limit break it.