Pipe Dreams: Expanding the healer pool

[Zumi]

Problem is that its super hard to balence healers just look what happened in FFXI throughout the years. FFXI had several jobs that could heal and even ones that weren't meant to be healers but healed so they could get in a party.

WHM, RDM, SCH, BLM, SMN

They always had one healer everyone seemed to go to or preferred over the evolution of the game.

FFXI Zilart to ToAU - The Red Mage dominance period
RDM was the go to healer, it had refresh it was self sufficient and could keep its mp up. If you couldn't get a rdm for your party you would take a whm, smn, or even sometimes a blm if they agreed to heal and just take the lower exp when they had to sit for mp. Allthough whm became a great healer with a brd but brds were even harder to find. RDMs were king of healers

WotG - Sch what is this a sub job?
WHMs started to become more wanted as they could now sustain themself with the /sch subjob and sublimation.

Abyssea Era - The return of the WHM as king of all healers
Goodbye RDM, SCH or anything else that could heal you don't have cure 5 and 6 and are pretty useless for healing people who have 3-5k hp in abyssea. The super powers granted by atmas let whms get about 35 mp refresh per tick basically making them the best healers because they were the only ones who could cast stronger heals cure 5 and 6. As players had such large HP pools rdms and schs were not effective healers. If you loved to play RDM or SCH you were out of luck because nobody wanted you for anything but in time things did change. Lots of people still do abyssea this day but once you go past abyssea you will see the rise of another healer

Post Abyssea - Voidwatch - WHM stays on top
WHM retained its hold on the healer spot during the voidwatch era. Atmacites while not as strong as atmas, and tons of temp items each fight made mp regen a joke once again you could just spam your strong heals on the people taking damage never run out of mp, however if your group was good and kept fanatics drinks up they never took damage so you didn't have to do much at all.

ADL, Neo Nyzul, Legion, Meebles, Neo Salvage era - SCH the rise to power
The current FFXI era lots of events are dependent on zergs with the abuse of Embrava the sch only spell which can only be used during their 1 hour ability. Embrava gives you TP regen, HP regen, and Haste all with 1 spell can be further enhanced with Perpetuance and used on group with Accession. You didn't need huge cures outside abyssea. When people figured out how powerful Embrava was it became the keystone to zerg down almost all the remaining content in the game. People plowed their way through Neo Nyzul to get game breaking gear on lv100 floor runs, 2 sch and 4 melee did the job. People used cor mules to reset their SCH's Embrava after each run. Even so SE nerfed it some in Neo Salvage however that didn't stop SCH from being the preferred healers due to giving the group EN spells, aoe status removal, and Embrava is still usefull on bosses even though nerfed. Sorry WHMs or RDMs your out of luck if you want to do Neo Nyzul or ADL ect since you can super buff melees with a broken spell Embrava.

[Duelle]

Problem is that its super hard to balence healers just look what happened in FFXI throughout the years.

We should keep in mind that no one from that developer team is working on ARR, with the exception of Matsui Akihiko. And unless Matsui is calling the shots in class/job design and balance, I am hopeful that mess will not repeat itself.

WHM, RDM, SCH, BLM, SMN

BLM and SMN are victims of poor role distribution between the 20 jobs. RDM design was botched from the start because they wanted a 1:1 copy of RDM as it was in Final Fantasy 1.

FFXI Zilart to ToAU - The Red Mage dominance period

MP regen as a niche for an entirely separate job was a terrible idea, and that period of FFXI's life proved it. Yes, RDM was self-sufficient between Refresh and Convert, but it also accentuated the problem with WHM's design in that it had no way to recover MP. The fact that at that point in time anything higher than cure IV was innefficient due to MP costs and overhealing only made things worse.

Considering spells were effectively shared, there's not much variation in terms of mechanics. People in XI didn't care much because they were that desperate for a healer, which takes us back to the point I made in the OP that funneling your healing into one job is bad for the game in the long run.