>>538934035
It's not that they "don't care", in fact the geno route itself has value in it's metacommentary that there are people who do it out of appreciation for it's messaging.
But when you played Undertale in a vacuum, you're meant to think about the game you're playing as a video game that has a beginning an end. Everything is made with intent, there's no "wider universe" to explore, it's a story with a purpose and themes you're meant to think about. The genocide route is you trying to go beyond that and realizing there's not much left, you get a bit more lore and character moments but was is really worth it?
When you start seeing the characters and universe as "real" you start to lose the plot. You don't care about the actual story anymore, you just want to consoom, be parasocial. Then you get absorbed into your idea of the game dictated by your own rules instead of the creator's. In other words you're playing dolls.
That isn't to say, it's wrong to get attached to the characters and world, and want more of it to be explored. As Gerson said, art can be reinterpreted and adapted in different ways. You can have a healthy relationship with art by using it as inspiration to create your own thing, or just be a better person because it's what the game told you to do.
God I fucking sound like an obnoxious breadtuber but I honestly can't stand autists that just don't understand why stories get made in the first place.