Look no one is asking to discontinue the mainstream MMO line for this. It's understandable for you not to enjoy XI. A lot of people do though but it is clear theres two play style preferences at play here and it makes sense to cater to those different markets. If XIV players want to hand in tomes for everything and only want to spend 10-15 minutes a day playing the game thats more than fine, so if they release two different MMO lines that share assets those that prefer a little more investment and longevity to their MMOs wouldn't be left out to dry.
If you look around and across cultures you'll find that people enjoy developing habits and stability. For example, if you to Miami and visit little Havana you'll come across a park called Domino Park. The people there have been playing Dominoes for 40 years and chill and hang out with their friends. They don't go there to play chess. They haven't changed their game. And nobody would shame them for it.
The same applies if you go to San Francisco and at the heart of the city theres a park where people congregate to play cards.
So its not crazy to think that the digital generation will have the same subset of people who enjoy playing the same thing over and over and this is largely who these slow MMOs will appeal to. Just like the people in the parks referenced above have families and jobs, its not like they no life the game 24/7 (invariably some will), these MMO players aren't the sweaty try hards you think they are. They're just people who prefer one game when they have time and they like to invest in it.
In fact, as the gray gamer generation spawns I can only see the market for this expanding. Old people don't like change. Now personally I'm not that old, and play a few other titles, but due to my work and life I normally main one game, and beat the occasional blockbusters like Elden Ring or Zeldas.