Enmity Mechanics?

[Atoli]

The obvious strategy against it wouldn't be to stop/slow dps or healing, it would be to use abilities that lower threat. Like Lyrica said, that would only lead to certain classes becoming mandatory for the content.

[AniCelestine]

When monks are given an ability equal to either qualling or elusive then sure, but that'd be a simple "oh I got this thing on me, gotta remember to pop this skill now" (or after if you're dragoon) so how does that increase difficulty. Would just make ninja mandatory if it's a dps check fight with frequent enmity modifiers thrown on dps classes. Say bye bye to monks.

[randysquirrel]

Sounds less fun and more annoying.

...is one way of putting it.
A mechanic where the OT has to try and shift themselves down to be #4 in the hate list ready for a mechanic sounds like a sh*tstorm waiting to happen. Imagine this in DF

*shudders*