The Defiance overall enmity boost is likely there to encourage you to use SE and SP more often now that they are both useful and have lower (in SP's case much lower) TP costs. Using a maim combo is basically a threat loss as it stands, and when your dps are going flat out, it can discourage you from using them. SE also increases PLD threat at no cost to them, which can also (but is less likely to) lead to issues. The overpower-specific enmity boost is the one that makes me chuckle, because I can already hold aggro off of triple flares when I'm berserk overpowering. The overpower AND defiance enmity increases make me pity my groups PLD for turn 4. What will he have to do?

More to the point of the thread, pacification does have fairly limited use at the moment, but for bosses / mobs that can be affected by it, it will prevent them from using any weapon skill. You can use it to make you feel like a badass when you stand in a dullahan's iron justice and he just decides at the last second to not cast it because you pacified him. Awareness is a completely unreliable cooldown even without the bug, and as it stands with the bug, it's not even worth having on your bars.