This topic was beaten to death on the beta forums, personal limit breaks would just become watered down flashy weapon skills, and the games flashy battle effects was a topic beaten to death also.

99% of the time this topic comes up it boils down to someone complaining they wanted to use the "big flashy" and didn't get to because it was better for another role to use it (Not talking about Ifrit HM, fully aware that can be done without a caster, just idiot proof with one) or they "accidentally" used it and wiped the group.

I'm for keeping them as they are, some fights hinge on proper LB usage and certain actions by the party accelerate LB bar gain (stunning certain attacks, killing certain targets in time, etc), changing this would just make it a spamfest of flashier weapon skills and would require a lot of fights to be completely rebalanced due to this. Just imagine all the melee trying to stun Ifrit's attacks for their 1/3 of an LB bar segment resulting in dead mages due to stun resistance building, then blaming the designated stunner with a practically useless LB in that fight.