I think there are delicate ways to improve FL

Bringing back 10 second immunity on CC.

Take some of these LBs and actions and give them fall-off when affecting more than five targets.

With the above in mind, take away WHM/SMN damage penalty but cap their LBs. Also lower damage reduction for all jobs.

Maybe revise the battle high system to monitor extremes in damage.

If you are going to SAM instant kill LB, it would be better if it could be readily identified on the target.