In simple terms?
Not playing Ultimate and/or not looking for groups for Ultimate.
Also "great many" isn't hyperbole. The majority of the playerbase are casuals doing casual content, where there's no great shortage of Healers. Tank is still AIN almost all the time outside of 24 mans (which only have 3 Tank slots to fill), where it's often DPS (DPS are also frequently AIN for Trials for whatever reason, but I've noticed Trial ques are almost instant no matter what role I que for them as...)
The long form Reddit survey had a lot of people saying they really wanted more healing requirements from the encounters, not more damage, they would just accept more damage as a band-aid fix, but it wasn't their first choice/desired outcome. Not sure about the majority on Ty's, though a lot said they want more support actions, not more DPS actions.
In fact, what I noticed the most from the long forum Reddit responses were people saying they DID want another DPS ability or two, but wanted them to be situational, not part of a standard rotation or used on CD situation.
The other part of the answer is this:
We're in a content lull. Most people that wanted to do the content (Ultimate, Savage, even Ex5) have already done it to death and are waiting for the next content drop. This isn't just Healers, this is also true of Tanks and DPSers.
The most frequent request for WHM seems to be Aero 3. Purgation as an upgrade to Misery would be hilarious, though.I do love hitting Purgation in PvP. Much more than stupid Seraph Strike, anyway, which is just "I want Protect and Cure 3 and have to put up with this button not just being the thing I actually want". I think Seraph is the button I use the least in PvP and the first one I'd change. Honestly I'd tie it's effect to Misery. Get rid of the dumb gap closer - seriously, who thought "healer runs into melee" was a smart idea??