While the current AI limitation is a set-back, from my understanding, it is a necessary set-back. Currently Physick + Embrace has a higher combined heal potency than Cure II, for half the MP cost. Being able to fine-tune Embrace would require Cure II's MP cost to be either cut significantly or the overall potency to be buffed significantly to keep it up-to-par. Part of the reason why it's balanced now is BECAUSE the fairy can't be controlled 100% of the time. The room SE gave for error is what helps keep things balanced.