Because, in a game that caters majorly to the casual playerbase, the more hardcore side of it aren’t allowed to have something designed for them? Every piece of content released in this game is catered to the majority—i.e., the casual playerbase. Just look at the Stormblood Ex primal: Lakshmi and Susano rolled over, Shinryu—while fun—is definitely not on par with Thordan Ex at release, and Deltascape Savage is about the same difficulty as Creator, if not easier. V3S, while a mechanic dance, is far easier than A11S. Neo, while fun, is easier than Alexander Prime. Point is, everything in this game caters to the casual crowd, yet they seem to be the ones that complain the loudest when content is released for the other part of the playerbase for once.
Considering there was thread after thread being made complaining about gating Ultimate behind clearing V4S and how “unfair” it was, I’d say enough people are interested in it to make it worthwhile to implement. If we want to discuss interest, I know a lot of people that are not interested in Ex primals—doesn’t stop the developers from making them. I, myself, am not interested in any of the new dungeons being released, because they’re just copy-pastes of all the previous dungeons with arbitrary gates set up to temper tanks that want to pull larger groups of mobs. Doesn’t stop the developers from making more dungeons. Same thing can be said about any piece of content: not everyone is going to be interested, and the content isn’t going to last forever. Considering SE had to put in an Alliance Roulette with a massive EXP reward to get the queues rolling for the older 24-mans....
In other words, it seems like you’re saying “I’m not interested in this piece of content, so it’s not important, and it’s going to die quickly.” Just because you don’t like something, or just because you have no interest in it, doesn’t mean that other people don’t as well.