A lot of tags activate/deactivate system functions that Apple doesn't allow 3rd party app access too. You'll usually get a prompt that leads to the settings menu. This is for security and privacy reasons.
So all those are out right out of the gate.
Than you have Apples app sandboxing (also for security and privacy) that will hinder performance of other functions.
While it could be useful it's probably not worth the risk of implementing. Since we don't have it we won't miss it. Android switchers might though but I wouldn't hold your breath.