There are many reason's you could be interested in reading the Ruthless Route.
1. There are many revelations that are too far from the main story. It's possible some of them might not even appear in the main game.
2. While you do have to hurt Asterion (and it sucks, it absolutely sucks), the Ruthless route is not entirely about that. You don't get to spend too long abusing Asterion before a certain shift happens and the real meat of the story becomes clear.
3. It's pretty short in comparison to the rest of the game, so even if it does hurt, it goes by quickly. It provides an unique conclusion to the MinoH storyline that actually ties some loose ends (albeit in a strange way).
That said, I don't think it's an obligatory experience. It's really good writing and art-wise, but (depending on which ending) you might get some uncomfortable or even triggering scenes, so I wouldn't judge anyone for not going for it.
I do recommend it though, it's peak Minotaur Hotel content.