I'm not 100% sure I agree with this. While I agree the Titania trial is not actually possessed of any really remotely difficult mechanics, I don't think it introduces nothing the game hasn't thrown at someone prior. At least, if the person in question has only really done MSQ content.
Because while none of those mechanics are new, I think some of them are ones that hadn't been used in normal content prior to Titania... or if they had been used, they weren't used often.
For instance, the 'starburst' telegraph that shows where her thorns will go; I can't offhand think of anywhere prior to Titania that those get used in normal content. (I may be forgetting one, though, I grant.) Similarly, things like sealing the puddles and then stacking in one of those puddles for the fire punch... while it's not unheard-of for normal content to have follow-on mechanics like that, I would say it is uncommon.
Add to that the fact that Titania has some sort of weird -- and entirely unwarranted -- reputation for being Super Difficult, and I've seen folks enter that trial nervous to start with. And being nervous about "oh god I'm going to mess up" is probably not the best mindset to make tackling potentially somewhat-unfamiliar mechanics feel like a simple task.
...to be honest, I don't use Fire I in my black mage rotation.
It's like... Fire III, Fire IV, Fire IV, Fire IV, Fire IV (if I've got the time/speed to pull that fourth one off before Astral Fire drops off), Despair, Manafont, Fire IV, Despair, Blizzard III, Blizzard IV, Thunder III, and cycle back to the start with Fire III. Obviously with some Xenoglossy, Sharpcast, Triplecast, and Swiftcast mixed in there as appropriate. (As black mage is my last DPS to get to 90, I don't yet have Paradox to work into that anywhere.)
That said, I also don't play black mage much -- or play it in any particularly high-end content, because it's 100% my least favorite job in the game -- so I grant I might be doing it wrong. (In fact, I am probably doing it wrong.) But that just feels to me like it should be the most effective rotation, and there's no place in there I see for Fire I.