HW dungeons are easy, but healers felt critical because without healers everyone would die. A healer forgetting to heal means everyone would die.
Yes, pressing Medica II every once in a while was easy, but if you did not do it everyone would die. That's why the content can be easy but the job is still critical.
Yes, because tanks and DPS had very little self-sustain. On top of that your healing oGCDs were also much more limited and less powerful, which means you required far more healing casts and healing actions.
Yes? It is not hard to heal a dungeon and making sure everyone stays alive. They weren't complex. But because tanks and DPS had little self-sustain, most people couldn't pull off a healerless dungeon run. Not sure how much simpler I can explain this. Was it hard to heal through Cutter's Cry? Was Cutter's Cry a hard dungeon? OK, go try it healerless. It'll be far harder than doing any of the EW dungeons healerless.
When content and job design are regressing, going back to the "good old days" is a positive. The old days were good. There is nothing wrong with pining for the good old days when the game was more engaging in the past. The current philosophy is something even Yoshi P regrets pursuing. Even the developer team does not want to move forward with the current philosophy. They want to go back, maybe not entirely to SB but it still shows that there is merit to the "good old days".
OK, maybe you believe /r/ffxivdiscussion or somewhere else is the pinnacle of quality gameplay discussion and so believe everything you've read. But I've seen absolutely NO ONE make an effort to disentangle HW's objectively poor job clunkiness, horrible job QoL like stance switching on tanks, and pointless systems like accuracy, versus the superior job identity, higher skill ceilings, engaging and unique gameplay like SMN's DoT extension or AST's time mage gameplay. It's easy to dismiss the pining for HW/SB as rose-tinted glasses, but it's much harder for people to justify why the positive aspects of the previous expansions cannot be brought back into modern FF14. It's so hard that nobody ever tries to tackle it and resort to the lazy attempt to dismiss everything as nostalgia.
OK?