I must say, Carighan and Hikari have the absolute right of it. I've played Black Mage since the beginning of my FFXIV career near the end Stormblood and I considered it my main job, once upon a time. But it soon fell out of favor with me because of how tedious and joy-killing it had become for me.
I knew its kit in depth (though I never really got around to adding Sharpcast in my rotations) and could reliably play all normal content (I still remember how I played the Cloud of Darkness Eden raid to this day and where I'd put my Leylines down), but I grew tired with it. One single slip up, one single necessary movement, one unpleasant target and your whole rotation could be ruined and your uptime lost. This wasn't fun. Nowhere near enjoyable. It caused me to look elsewhere and that's where I found Summoner and Red Mage.
Here's something to consider: I always play mage-type characters in every game. It's what I'm naturally drawn to and enjoy. All three mage specs in WoW. Wizard/Sorcerer in Baldur's Gate 3. Astrologer/Sorceries build in Elden Ring and Dark Souls. The list goes on and on into the stream of time. So I know what to expect often from these sorts of classes and through almost all media, I excel in these fields since it comes naturally to me. Across most of these games, spellcasting mechanics and movement can vary wildly (I have the most fun with it in Elden Ring/DS and BG3 and, to an extent, XIV).
With that said, as I mentioned before, I had grown distasteful of Black Mage due to how it played and how tedious it was to do anything when other casters were more enjoyable even though I knew how to play (and still could) Black Mage. When I heard about the changes, I was skeptical and almost hopped on the bandwagon of "changes bad, simplification bad". When I actually decided to *play* Black Mage post-changes, I was swiftly proven wrong. Just the simple removal of the timer and the slightly faster cooldown of some abilities was like a breath of fresh air. As if the old pipes had been oiled and ran smoother than ever.
Funnily enough, I didn't find it all the much more different to play than before. But it was more enjoyable and still had some of its earlier edge in placing your Leylines correctly/optimally. It was magnificent just how the removal of the timer on Astral Fire and Umbral Ice improved my experience so much. The only critique I would have to say is that I would like Paradox to be more meaningful and have more mechanical impact than it just being another Xenoglossy/Foul. Thunderhead being permanent is meaningless. Fire III having a timer on it *could* be good giving somewhat more complexity, but again, it's not terribly impactful.
What I'm most happy about is that like with the other casters, I don't have to have my attention split three ways now and can more fully focus on the boss and mechanics.
All in all, I'm largely happy with but a few critiques. That is all.