TLDR: "Me special, me not like those filthy parsers".
Now if you weren't too self-absorbed, you'd go and see (in that compiled thread) that people that don't do savage or even raid making threads/posts about wanting Kaiten back. I have yet to see anyone complain about losing a deathblow, which every job had removed at the start of ShB, and you just "want it back" with no reasons provided other than "it looked cool", which is also a reason we all want Kaiten back. You shooting down something because "me speshul" will backfire, and here it is.
"I don't use Kaiten so I don't care". I started playing the game just before 5.2, I didn't even know this terrible skill called "Ahega" existed till now, let alone use it, so I should also just dismiss it out of hand, and I have no qualms whatsoever doing that. It was a terrible skill with 0 use in any situation. When I mentioned this thread to a few of my friends, the response was "Oh that Ninja-adjacent shit? I am glad it's gone", and those are people that have played the game since Heavensward, and guess what, I will agree with that assessment. The animation was just a slightly longer Shinten, the functionality was absolutely god-awful that I am glad it's gone so I didn't have to see that in my hotbar when I started playing.