Agreed, the damage reduction across the board is ridiculous. Certain melees already were naturally better at survival due to useful ranged tools (NIN Fuma Shuriken, Hyosho Ranryu, Goka Mekyaku) or mitigation (DRG Roar, SAM Chiten, Meikyo Shisui CC resist), so a whopping -60% reduction (i.e. over double of effective HP) was massive overkill.

If their worry was the LB nuking of Afflatus: Purgation, Summon Bahamut or Sky Shatter, then they could've implemented LB damage coefficients to reduce LB damage further and keep damage reduction at a more reasonable level of like 20-30%, so the normal tools don't feel like wet noodles.