As a tank i'd rather never use my LB, because it usually means that shit has hit the fan (and even then a healer should LB) or the fight actually needs a tank's LB, and if we miss that it has high chances of wiping. Besides, what's fun to some might not be to others. I had lots of fun leveling a tank, just because I felt usefull playing as one.
Couldn't agree with you more, its totally doable with a MNK / DRG / 2 WARs but then again, when people start doing Ifrit they are probably: using every single skill on their CD or isn't paying attention at all to the boss to actually stun it. So they prefer to have a PLD as stun ho just to be on the safe side. Ifrit IMO is the first fight you really need to pay attention to or you can wipe easily.