To expand and clarify some of my points above (Sorry, had to head out and missed important details in the process)

Regarding BarbEX. The thing that makes BarbEX a fun fight isn't the incoming damage because it's mathematically demonstrable that it's not actually that high in the grand scheme of things, it just felt that way after ZodiEX which did a lot of nothing, HydaEX which was a soft touch and EndsingerEX being a slowly paced puzzle. Where BarbEX shines is the pacing of the fight. She's winding up her next mechanic whilst the previous one is still resolving. There's relatively little downtime, if you take your eye off the ball for a few GCDs after resolving one mechanic, you've likely missed the start of the next one. It was that pacing and pressure that made mechanics like Knuckledrum feel good.

So yes, content design definitely has a lot of room to improve and even as someone who's been around and on the edge of world prog since ARR, SE's current 'esports friendly' design approach to high end content just feels super strange and at odds with the rest of the game to me. Sudo's designs were so much more organic and less 'by the numbers'. By comparison today's bosses feel like a box ticking exercise. AoE 5 seconds into the fight to remind healers that we care about them? Check.

Next up, expanding on healer kit design:

Look at it this way, take 2 BLMs in a soft 24 man like Aglaia. #1 is an absolute try hard with the talent, experience and knowledge to back it up. #2 has read the tooltips and knows to keep their GCD rolling but doesn't have anything like the same experience or knowledge. The #1 will decisively beat #2 even in this face roll content. This is a big part in why so many think so fondly of the job. You put the effort in, you get a reward out.

Now apply the same to 2 WHMs. #1 is my usual co-healer Fretty, quite literally a top 10 ranked SCH worldwide at his peak, #2 is me, a meme at best, a HPS monster at worst. In casual content like Aglaia I can match him or at the very least run him damn close. This isn't because I'm good and it's not entirely the fault of the content because after all, there's a clear gap between the BLMs. The problem is that as long as I'm mashing keys, it's very hard to press the wrong one without doing something REALLY stupid as a healer. The only reason why Fretty and myself are likely to gap other healers in the raid is because they are mindlessly overhealing or simply don't care.

And that right there makes up the bulk of the skill curve for a healer in your average 24 man raid (or other mid tier content) right now. Do you actually care? Can you watch your screen? Can you read a tooltip? If so, congrats you can likely keep up with some of the most talented healers this game has.

That is NOT good design by any stretch of the imagination.