Just throwing this out there, as it occurred to me... you know /Heal, how it generates enmity (or just raises your place on the enmity list, not exactly sure, but everyone knows /heal affects enmity and does something to increase it in some way.

What if it did the OPPOSITE, every "Tic" that you regain HP/MP, you also lose say 20% of max enmity, perhaps modified by Enmity- gear, so on Monk, instead of just turning, I could've ran a bit away, /heal'd for 30 seconds, and then have been able to hop into the battle fresh and been able to properly DD for a while again.

No scary "imbalance" because people still can't go crazy damage wise without consequences, you don't have to add any new JA to every job to help with enmity, or anything like that.
That would actually be a good idea. The problem here isn't enmity generation or the enmity system but the utter lack of enmity reduction abilities in the game. Many other MMO's give their various jobs enmity shunt or cool down abilities that need to be managed, FFXI only really has HJ/SJ which won't protect you from aoe's. The /heal idea works very well for this.