Focusing on healing combos could save mp in a fight if perhaps the combo would reduce mp and cause regen, or something. Also, if using cure would lead into a combo with cura that could be curing two players, one for a little and another player for a lot. Or if it cut down casting time in a combo for a quick-saving-the-fight kind of heal. It could make players think more tactically with heals, but I agree that more healing spells in game could help merit this idea.