OP's idea is indeed quite novel, and before freaking out, I think what he (or she) implies here is something I'd call Implicit Emnity where the mobs would naturally go after healers or someone that's dying. With provokes being taken away, tanks can be given abilities to cover other players, defensive bonus to those who stand behind him, and to pull the mob physically away...etc.

However, in order to make this work, the mobs need to have very sophisticated AI which are very expensive to implement. Also it's easier to exploit mobs' AI in this case when they're becoming predictable.

Anyway, I doubt SE would make such a big change for FF14 but nonetheless it is a profound idea!