Cure 3 was useful to me in TEA and PF. You can also use Plenary with Cure 3, as well as Asylum and Temperance. It adds up quickly. Because you barely use it doesn't mean it doesn't have uses. BRD has an ability called The Warden's Paean, it's completely useless 99% of the time since it's used to remove debuffs.
It used to be the case that you would use lilies for movement in Shadowbringers. It's not as much of an issue now with reduced cast times, but you still can't heal and move quickly at the same time. Blasting an Afflatus Solace on someone who messed up a mechanic means you don't have that lily for later. That can screw you over on some mechanics where you need to move but also heal players.
WHM just doesn't have enough buttons to justify merging lily skills into the regular GCD ones and it takes away that choice.
Let me ask the same question then, if you want to heal only using OGCDs, why are you playing White Mage?
I frankly do not understand this line of questioning where healers exist in this universe where no healing is ever required. I've played in all sorts of statics, including casual ones where the healers aren't that great, and PFs where healers are very disorganized and sometimes value their damage over healing the party. In these situations, you're going to need those lilies.
Lily abilities are also more efficient and don't cost mana.
Medica II:
- Costs 1000 Mana
- Opportunity cost of 310 potency (1 Glare)
- Heals for 1000 potency after 15 seconds (0.31 damage per healing potency)
- Requires you to stay immobile
Afflatus Rapture:
- Costs no mana
- Opportunity cost of ~115 potency
- Heals for 400 potency (0.2875 damage per healing potency)
- Allows you to move
That's not to mention that Rapture can apply Indulgence more than once, while you tend to use Medica II once, which makes it even more efficient. Then you can use Misery inside a buff window. Let's say that you have a Monk, a Bard, and a Monk. Their buffs will give you a 1.06 * 1.05 * 1.05 damage multiplier. Ergo, your 900 potency misery now does 1050 potency, that's not to mention the Direct Hit buff from the BRD. You're effectively missing 190 potency in this scenario for 1200 potency of party healing or 2400 potency of single target healing.
Of course that's going to depend on what you want to do. If you want to argue it on a purely DPS basis, you're always going to take Astrologian even if the white mage never heals and only casts damage spells. Astrologian just does more damage than White Mage right now. I'm not going to disagree on the basis that Misery damage doesn't need a buff, I think it does. But I don't think the intent of the original design was for it to be DPS neutral.