I don't healer main but I've been playing one since HW and what I have observed is this:

ARR: Jobstone shenanigans to manipulate cross class skills. Healer main? HA! Not if you don't have a lvl 15 Thauamaturge (for Swiftcast)

HW: Cross class skills were reworked a bit but hey, that new healer we came out with? Doesn't have Esuna. Better get that CNJ to 15. And if we see you using Selene (other than very specific instances), you will get heckled. Best times.

SB: Cross class skills become role skills. Most for healer get stolen from WHM. They add instant heals to make up for it (to WHM), and a new nuke. Pet actions go away (because only 10% of hardcore mains used anything beyond Sic) and Selene losses the one thing that made her great (the instant multi esuna). Now you can use the fairy that matches your glam! Red mage becomes ad hoc third healer in clench situations.

ShB: Support skills are abused (by idiots/Tanks) to the point that they are taken away and the roles are stripped down to their most basic functions. Still no new healer class. The community is traumatized by reddit talk to the point that new healers feel pressured to dps to the point that they let people die. Tanks start asking/pleading for healers to heal them (this is real and happens multiple times). Tanks are removed from god tier and more 'green healers' emerge to... Do mediocre dps I guess.

EW: Shield/Mitigation Heals and HoT heals are now two distinct schools of healing. Bloat is reduced. SCH finally loses that last fig leaf that connected it to ACN. Other than Sage, nothing exciting happens. But healing is a lot easier (or not too different anyway). It's just...meh.

And thus is the path of the healer. RDM is still 3rd healer and SMN is now a completely different animal. But I can't say the journey has been bad. Just interesting. Hopefully they'll add some flavor back someday.