I main BLM, but I'm leveling up both WAR and PLD, so I can a bit understand both sides....

as a BLM, my Quelling Strike usage is kinda situational.
I usually look at the aggro list, whenever I'm going to use Flare (even when convert is not up), so if I see that the aggro list is "safe", I save up Quelling for another occasion.
I usually don't bother with Quelling Strikes, if I'm way overgeared compared to the tank, and there is just 1-2 mobs close to death. I'll eventually pull from the tank, put on Manawall/ward and burn them down.
I don't use Quelling Strikes either, when I see that the tank is REEEEEALLY bad, and just lose aggro every time I cast fire1.

on the Tank side, I find it hard to lose aggro from a BLM, unless he is like in full poetics gear and doesn't give a rat's ass about aggro, and I'm sitting at lv30ish gear.... I don't even bother taking the aggro back...

what I find really frustrating, are triggerhappy bards. these folks like to pull earlyer, not even bothering to wait till I use Tomahawk/Shield Lob
generally speaking, i can't stand dps with 0 vision of the other party members.
It happens, sometimes, that while I'm getting closer to a mob so that I can use Lob/Tomkahawk, I get aggroed form a near mob instead.... by the time I cast 1-2 Flash, the've already started dpsing everithing that moves.
or, even worse, people that while I'm doing my rotation on a group of mobs, they go ahead and pull to me another one. just because they're sick of doing the dungeon for the Animus book.

oh, and let's not forget Triggerhappy WHm with fluid Aura. I want to kill them all.