People in this thread haven't been pony farming much eh? Many of the Primals strong LB attack interrupts casting. As a white mage, to be able to surecast and charge up a medica 2 during leviathans LB feels pretty damn good when it goes off immediately after the damage hits the party with no interruption.

Another example would be in ST on the last boss when he does Ancient Quaga (spelling?). If you time it right as a mage, you can continue your rotation with a surecast (spell) when the lightning cloud goes off so that you are not interrupted. On black mage, when he re-appears from sending meteors down at us, I use a thunder 2, stack with the group for the lightning cloud, then surecast fire 3 and it guarantees it will go off. Definitely allows for more damage in the long run.

So the point stands that it is still very situational, but it does feel good to negate an interruption from a huge attack that would otherwise interrupt you.

I agree with many posters here that I would also like to see it slightly buffed. As for a suggestion for the buff, I'm not exactly sure. For me it does seem more of a pvp ability.