I'm sure I'm not the only player that has issues with this, constantly having a Co-tank on me its irritating that we both hit Enmity Cap on a mob (something that should be front to back tanked) and have it spinning around on us.
Certain mobs have instant death gaze TP attacks and with a mob constantly spinning around because both players are at enmity cap it makes defeating such foes without risk of death ... a death trap ironically.
Even on my White Mage I have no problem hitting Hate cap with enmity -50 after a few dozen cures on some NMs that take longer to kill, even with Beguiling Collar when I eat hits, the additional enmity loss per hit does not warrent enough for me to be able to re-cure myself so I'm not in any danger of being killed during an AoE attack from wyrm/sandworm/mob w/ Ga spells when running in to cast barspell/auspice/shellra5/Esuna.
Fairly sure this would also remove some of the issues with Paladin and its problem of lack luster tanking currently in the game with abyssea, albeit players could still play other jobs and be just fine, those noble players that enjoy playing their favorite job would most likely be happy.