The Traveller may be unvoiced, but they're far from a robot. The story has characterised them as stubborn, kind, cocky, curious and cautious. And I'm not talking about the choices, those are just traits of how the Traveller is written.
It's easy to pay less attention to it under the assumption that the traveller is a self insert, but once you distance yourself, Traveller is more of a rounded character than many an rpg protagonist.
That said, I think a lot of the "issues" with Genshin's story stem from two things:
- It works like a stage play. Limited visual presentation due to things like download sizes mean they use a very minimalist style for a lot of the story telling. This combined with being stuck on one single character and an open world format, means things like time jumps feel less natural, and more suspension of disbelief is required (like with a stage play)
- The game spells out its simpler concepts through Paimon's summaries, but not its more complex ones. The players tend to take a very surface level interpretation of the story, and then when more complex concepts come up, they take it as a mistake rather than an intent.
As an example: Eula's Quest, many people assume you're just meant to feel bad for her, and that her being dysfunctional is just the writers not knowing how to write. That's just not true. She's meant to be dysfunctional. A guy calls her out on it in extreme detail. But because Paimon says people are rude to Eula, players assume that should be the only takeaway. Even though Paimon is not a narrator, but a character who is often wrong about things.
Raiden's quest has a similar issue. People tune out because its initial premise is mundane, but neglect the amount of philosophy and introspection that goes behind it. They assume it's just a date because you're going through town, but it's always about her relationship with her people, not with the Traveller. Heck, a lot of people seem to have taken Yae's comment about Raiden being a sulking otaku at face value, even though it's pretty clear Yae loves spinning the facts, and Raiden hasn't touched a light novel in her life before the quest.
Same goes for Gorou and Kokomi. Yes, Kokomi is a genius. In theory. The issues she has with her army, and the ways in which things tend to go wrong, those do not disprove how she's smart, they just show the ways in which she isn't. Kokomi is a textbook gifted person: Smart on paper, very capable in what they're good at, consistently under- and overestimated by peers. But players quickly assume this is just an oversight, and Kokomi should be smart in all regards, even though it's the actual story that she's incapable of handling all aspects of the job.
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Something important to consider is just how different Honkai and Genshin are at their cores. They share a lot of concepts and thematics. However, Honkai is like an anime series brought to multimedia through manga, game, VN etc... Where everything is built around the story.
Genshin on the other hand is an interactive world with stories inserted into it. A sandbox of lore if you will, with very different challenges. And imo, a lot of the criticisms leveled against it don't hold up well under scrutiny.
This also explains why events, and character quests focused on established characters are regarded much stronger storywise: They tend to be much more isolated and less introductory. Whereas Raiden needed her story quest to show us who she is as a person, Venti no longer needed that introduction. The current event takes us to a locale we're familiar with, using characters we already know, to play out a more traditional ensemble cast story, and it works.
This is why Genshin's writing will likely be an up and down process for many. Established ideas and characters are just much easier to process. New ones however, consistently have to live up to false expectations.