I am a healer who is not participating in the strike (although I agree with every complaint,) and I would like to share my experience playing through Dawntrail so far.
My job is Scholar and I have been doing the MSQ with it, for Science (tm).
First off, the good: the first trial (I have done but one) was engaging. I am pretty good at playing the piano to keep people alive and I like to do it, especially when things go south while I am in the middle of learning the mechanics myself. I had a lot to heal and a lot of opportunities to pick people up off the ground or save them before they got offed by an upcoming mechanic. I was able to engage with the game as intended.
Now, the bad...
Of course, what the strikers already know: healers barely have a gameplay loop of any kind for either healing or dps. Right off the bat, questing in the overworld, I recalled that I have little to do vs enemies but press 1 really hard. I fully realized how awful this felt when I ran into some Hunt marks in the 96 zone and remembered that Scholar was my only mid-90s job, so I had nothing fun to switch to to kill them. Pressing 11111 to down an at-level mob alone is genuinely soul-numbing, and pressing my 2 minute cooldown for one or two overworld enemies because I am desperate to do something else is not a good feeling at all.
In Dawntrail dungeon content, if even a single other person in the party has seen the instance before and is able to avoid the telegraphed mechanics, there is very little interaction with the game for me for the full duration of the instance. I may toss out an Expedient or a Sacred Soil to feel as though I am contributing by providing my fellow players some extra breathing room, but I do not feel as though it has ever made a tangible difference. If the tank knows his job as well, there is nothing for me to do at all during pulls--in these brand new dungeons that I have never seen before, remember!--except admire the scenery, observe the mechanics, and press Art of War/Broil while my fairy casts Embraces that are overheals next to the tank's own, faster self sustain. There have been boss wipes of course, for want of knowledge, but after those, my fellows are usually converted into 'seen the fight' players and have no problem avoiding the mechanics thereafter, once again alleviating me of any need to carry out my primary duty. Or play the game.
With these experiences fresh in mind, I would describe the Dawntrail Duty Roulette healer duty as being a babysitter while players learn how to do a set of mechanics, whose greatest contribution will always be Swiftcast+Raise, and whose job usefulness disappears completely once the mechanics are learned, given a competent set of teammates. It is bad enough that, when I played through the dungeons again with my friends in premade parties to help them level alt jobs, I could see clearly that my choice of job was a burden to the speed and efficacy of the run simply because they are all good at the game and do not need such training wheels to succeed.
To be clear, I have not yet completed the MSQ. The most recent dungeon I have completed is Level 95. So, to reiterate: I haven't even finished the MSQ or gotten endgame gear yet, the game is/was in early access which means all the content was brand new. Under these conditions the experience is still this way.
We will see if the notorious Lv. x7 dungeon shakes things up at all in the honored tradition of Bardam's Mettle, but my expectations are low and my disappointment is high. I am not surprised, however. I quit healing at the start of Shadowbringers because of how bored and bothered these changes originally made me feel, and two expansions later, nothing has changed at all, except the delivery of the PvP kits--proof that the design team can give us fun, unique things, but for whatever reason will not do so for 99% of the game's content.