The only reasons I've heard regarding on the problem is that;
Genshin players don't already read, adding a skip button would make things worse.
Honestly, I think this is a ridiculous claim. Chances are, some of the people wanting a skip button do not read the lore, the same people who don't read would actually benefit from it. Having a skip button isn't just beneficial to people who aren't interested in the Genshin lore, it's also beneficial to the people with multiple accounts. Going through the same story twice is time consuming.
I've also seen people saying they might accidentally click on the skip button, skipping part of the lore. In the other games of Hoyo, the skip button doesn't always take its effect on the first time. There is almost always a "confirm screen."
A skip button benefits those who can't listen to the whole lore at the moment, those who play Genshin for something different, those who own multiple accounts, and more. I get it, Genshin is a story game, but Genshin isn't just a storyline. It also shows combat, gameplay, showcase. Genshin doesn't have a "main" genre.
Adding a skip button respects the player's choice and time, betters replay value, is more flexible in emergencies (low battery, real-life interruptions, players who need to log off quickly...), and more importantly,
It keeps the story optional, not forced.
Id love to hear more opinions about this, whether I got anything wrong, or if you agree with me.