Why don't Tanks have attacks that can cleave multiple enemies?

[Anienai]

With some attack animations you'd think attacks would hit an enemy and all those in the arc of your weapon at reduced potencies per enemy hit.

There are quite a few enemies and bosses that can cleave the party but as opposed to player controlled stuff it is practically nonexistent outside of concrete AoE only attack skills like Flash/Unleash/Overpower.

Attacks like Storm's Eye, Spinning Slash, Savage Blade should definitely hit multiple enemies based on the animation alone.

Many times I've noticed complaints about PLD's lack of AoE options, wouldn't the concept of attacks with a reduced splash damage effect help them out in that case?

Just something I've thought about.

Maybe with the new xpac RDM (or w/e new tank class) could feature this ability. Something with a short duration, but almost enough to make it worthwhile.