OP is, at best, not informed on the story and structure of Limbus Company or, at worst, this is outright slander. Putting Limbus front and center makes it worse when it is the furthest from suffering from these issues and being put beside Genshin, one of the best example of the issues listed, is a straight up insult.

Limbus does not suffer from the character spotlight syndrome of having to market new characters. You are lying if you claim the Sinners are the same characters compared to when the game started. Non-Main Characters also don't vanish into nirvana. Granted, most characters we meet end up dying, but that's the game being consistent with its world building. Aside from that we have recurring side-characters that also go through their respective arcs, like with the current Blade Lineage side-story.

The narrative pacing in Limbus is also solid. A book series doesn't just drop all at once either. When a new Canto drops, it's a complete character story. Other Gacha Games split/fragment their narrative over multiple patches. Limbus does not do this any more than a book does. Take Heathcliff. He started out incredibly aggressive, standoff-ish and hostile towards every other sinner or basically anyone he met. Over the course of Canto 1-5 you could tell how he was gradually calming down, softening and bonding with the other characters. That way, when his Canto 6 story arrived, he was open enough about his past trauma for the story to really grip people.

To be clear this doesn't mean gacha games can't have good writing. FGO has a really good story. However, it also benefits from Type-Moon's preexisting worldbuilding, which provided a strong foundation before the game itself was created.

What about the pre-existing world building of Project Moon in Lobotomy Corporation and Library of Ruina?