Implying there is any real teamwork in the current LB system to begin with.

There is no teamwork in telling your lowest dps melee to press a button because a guide told you so.
Say that I'm a summoner in a duty, I don't interact with that guy who presses the button at all. My characters does this o/ while I do this :| and continue my rotation as usual.

There is no excitement to be found in seeing someone else press the button you want to press.
Imagine how tanks must feel. There's a grand total of three fights in the game that require them to press the button, and we outgrew two of them because gear and echo. Good stuff.

Personal limit breaks is an opportunity to make limit breaks more individual instead of clones with different skins shared between jobs of the same role. And an opportunity for tanks, healers, casters and ranged to break the limit more often because melee LB is just too good and is the only LB that never becomes useless.