Innocence and Zodiark generally don't let one person wipe the party. Everyone is responsible for themselves, and there are no EXACT locations any players need to be for most mechanics. Where you bait the sword line/T doesn't matter as long as you don't run it through the party. Whether you go to the front or back of the field for Zodiark's diagonal rush generally doesn't matter. There are no mechanics with party spots, no in-out paired mechanics, no teather you have to swap between people, no light party stacks OR spreads. Zodiark requires the party to stack for the lasers and DEBATABLY the bait puddles super late in the fight, Innocence for the line laser which you also have to use at exactly one point to blow up a far star to create a safe spot. And I think both have a Tank swap. The big thing - the disorder - is that they aren't the same every tie. Innocence targets random players with the sword lines, and I'm not sure if he throws out the swords to the same spots around the arena (for the return trip) every time. The people in the later phase targed with the 3 prongged AOE lines are also random, as are the people targeted for the line AOE. Zodiark's mechanic sets come in patterns, but the rotation is random. His sweep across the field is random. The Snakes he summons with Akadia ground pounds are random (sometimes the front one is on the very front line, sometimes it's one space away from the front of the grid, so the party has to adjust), and the meteor patterns, while there are a few sets, are randomly chosen. That is, you can't just memorize the fight, as you have to adjust to the parameters adjusted, hence less orderly.
Contrast Titania and Hydaelyn. Each have some of the list of party coordination things I listed above. It's been literal years since I've done Titania, but offhand, it had water puddles, light party stacks (in puddles and possibly rotation), two sets of tether tradeoff mechanics, 3 adds where 2 required tanking and ideally focused fire to take them down quickly to reduce the number of overlapping mechanics, and her in/out runes that she'd use which also had to be worked out with the puddles, maybe a tank swap in there somewhere, too, I don't remember. Hydaelyn has stack, spread, and light party stack mechanics, and these repeat several times with other overlapping mechanics. She has in-out abilities, sometimes paired sometimes not. multiple cleaves by role, that require players to not only stack by role but also do so behind crystals to not get clipped by another mechanic. Chackrams requires both coordinated stacking and movement (people have to stack in two parties correctly in the initial safe spot and then yolo out of it), and the last phase also requires two sets of party stack, spread, and somewhere in there a light party stack. But both of these happen in VERY strict and set patterns, with only a little variance.
Titania's only variances are whether the party has to rotate clockwise for the light party stacks when the vines come out, who is targeted with the stack and which two with the spread markers in the add phases, who is targed first with the teather, and the order she does the in/our rune the second time. While that seems like a lot, the order is very structured and there aren't a lot of variations. Compare Titania Ex's puddle spawns (always the same spot) to P5S's (which are not). And her in/outs are paired. Hydaelyn does a similar thing with her three stances, and for much of the fight, the stances are always the same (like her always using the Tank stance after...I think it's after, been a few months...Chackrams, where she also uses spread/ice there; she also always uses Water [light party stacks] with Chackrams, never Earth [full party stack] or Ice [spreads]). In fact, a lot of the "random" stuff isn't. At several portions of the fight you might initially think she randomly uses a stance and element, she ALWAYS uses that stance and element at that point in the fight with those mechanics. I think she also always uses Water for the Lightwaves (first set) at the end after the spread + tank stack mechanic. In theory, they could have programmed her to use any of them...but they didn't.
The variations that those two fights have area also smaller, such as an in paired with an out, which is a bit different and easier to predict and react to than...Snakes with a random choice of spawn pattern and rotation.
As to why to pair them up - because it's the logical pair. Even the rewards (weapons vs accessories) are paired up that way. Finally, people wanting to compare them the other way to make the case that EW's aren't really harder/are less hard by comparison, leading to a faulty conclusion. There's nothing "random" about trying the MORE LOGICAL pairing.
If we went back to SB it gets weird, as Lakshmi was the more ordered (use of Vrill at specific points in the fight, specific ideal places to drop the AOEs) despite being the accessory one with Susano being a bit more random with targeting and such and dropping weapons, though both of those fights were more scripted owing to the way mechanics were designed back then.

Originally Posted by
ForsakenRoe
the only way to designate fights is the order you do them in the story, EX1 EX2.
That makes ZERO sense. We're talking about mechanics, not narrative. Hell, even if you paired them up by "what reward drops" it would be Hyd/Tita and Zod/Inno.

Originally Posted by
ForsakenRoe
It sounds like you're trying to ascribe a design decision to Hyd/Zod based on their Light/Darkness lore thing, which is just weird.
No, that's what you're doing with the Ex 1/2 thing based on when you encounter them in the story.

Originally Posted by
ForsakenRoe
To try and say that (from a lore perspective) Titania, king of pixies, who are known for playing tricks on people and being generally unpredictable in their behavior/temperament, is the 'orderly' fight? And Innocence, the 'literally a being made by the corrupting effect of a pure Order-aligned element (Light, in FFXIV lore)' is the 'not-orderly fight', is nothing more than a case of 'I struggled more with X than Y' in disguise, I think.
Maybe you should have waited for my answer (above) before making this statement? As it seems to be pretty embarrassingly wrong now... <_<
As to the getting better...
My biggest problem with Titania (and Innocence...AND Hydaelyn...AND Zodiark...) was more PF. As you say for Titania, "me
and the group I did it with watched an overview guide". I was teaching people mechanics in PF. I did that with Titania, Innocence, Diamond, and Warrior of Light (in that order) as well as Hydaelyn and Zodiark. Playing with randoms in PF gives you a MUCH different experience than playing with a Static or other skilled players. Heck, my PF P1S and P2S runs were often "Everyone gets it but 1 or 2 people...and they wipe the party."