Because you can fall out of love with a job and role. Healing has been getting increasingly stale to the point that people often joke that it's a discount dps with extra responsibilities instead of being a full on role in it's own right. At the moment all red mage is missing is a AoE heal then it would be just like any other healer right now.
If that arguement was to hold water, then why didn't they make a ranged dps for stormblood so then everything would've been 3? That's obviously not the reason behind their decisions that they claim it to be.
But this is of course assuming you count the sub roles of dps to carry equal weight as the heal role in it's entirity. By using that same logic, we only got 1 pure healer role, one shield healer role, and one buff healer role. So now we need 6 more healers to address the balance, and need 2 more tanks so all of the sub roles are fully catered for. Breaking up the dps doesn't stop them all being at the end of the day, dps.
Which when we get down to it. We've had 2 new tanks from ARR on (Drk Gun) 2 new healers (sch ast "Counts less since we only had 1 healer to start with) And 6 new dps. (Smn nin mch sam rdm dnc) to have a total of 4 tanks 3 healers 10 dps. So... Dps has had 3 times the jobs releases 3 times the jobs total. Yet were being told "But it was soooooooooo important we had a extra ranged dps with supporty elements! What kind of new healer could we need anyway!?"
It's not just that were not getting a new healer, but the excuse given is the same reason we were given 2 years ago. With every balance change making the healers more samey.
Also don't conflagurate people who are actively unsubbing in some form of protest. I personally am unsubbing because I was hoping for a reason to remain subbed. As it stands the only thing that is keeping me going is the story. Am I being a child because I'm just not really enjoying the game in it's current state and was holding out for fanfest to give me a reason to keep playing?
I'm holding out for the job rework live letter. But unless the changes are particularly significant, and getting healers back on the right track. Best case scenario, I'll be taking off my heal main mantle for something else.