I find it annoying while tanking (especially on DRK with Blood Price up, I need those hits to regenerate mp).

I find it annoying on DRG when trying to time that last Fang and Claw/Wheeling Thrust hit to refresh Blood of the Dragon for the next set of mobs.

I find it annoying on NIN when trying to time that last Armor Crush to sustain Huton for the next set of mobs.

In both DPS situations, it's supremely annoying when you get in position to activate the skill, just to have the mob go flying off.