It's a good point, though I don't see a solution myself.
You could increase the stats of lower tier enemies as per usual progression in FF game (recycled enemies with higher stats) which would bring the amount of mobs down, though balance would be needed so we don't end up with the extreme left like in FF11 where you need 8 people to take down a single Goblin which was half the size of the axe being swung at it.
The issue thereafter is still that pts will generally use AoE to fight a group of enemies greater than X.
I've always wondered how it would work if AoE's were area based, so if you have say 10 enemies in a confined area on the tank, the damage of the AoE would be spread out based on the level of mobs, their position relevant to the epicentre, and if any of the mobs in front of them would act as a 'shield' and lessen the damage done.
Once again though, I feel we end up back at the "PT's AoE spamming".
Like I said... I don't know of a possible solution. I think if there was, SE would have implemented it by now and if not, may implement such either in/post 2.0
