Why should they make a new healer when they have a hard enough time balancing the 3 we have? Not to mention you could literally remove the WHM lily system and the job wouldn't change. Astro's have 2 useless cards (Spire and Arrow) while the cards RNG being meh at best. Getting 6 boles in a row is a joke. Finish balancing and fine tuning the current healers before adding a new one.
On a side not, Dancer as a ranged dps is odd, but it is a physical DPS which we only have 2 before while we had 3 of Melee and Magic Ranged. A new ranged DPS makes sense so long as it is physical.