I don't find it exploitative but rather artificial meta gameplay. I don't like such tactics (that's why I don't play Tactician).
Anyway, it has nothing to do with taunting. A taunt is quite useless if blocked by armor. When armor is gone on all targets, the fight is usually over quickly. I would opt for armor ignore for taunting. We already have a very annoying exception of armor ignorance in the case of oil (I really do not like this), make another for taunting, in this case even with some sense in it.
Exactly, making taunt ignore armor isnt making it op, you are sacrificing yourself and your defense for the sake of your team, that means your team have to keep you alive. Or you have to build pure defensive at cost of AP.
In fact taunt doesnt even work properly, i had a taunted magister/blackring just outright ignoring the debuff and start attacking my summoner instead of my summon >:(
