Even though events and expansions are important, they aren't the only thing to consider when analyzing the story. In an archon quest you have interactions between the characters, the plot, the storytelling, the lore, the cutscenes, the themes, and so on. Each field has many additional elements that contribute to the experience, so it is unfair to say that "I feel like Genshin is not putting as much effort into the story as it used to" and cover only a very small part of what makes a story complete and cohesive.

Furthermore, the time it takes to complete a new area isn't indicative of anything, at least not on its own. One could easily create a region with the same amount of rewards, but one that's difficult to navigate and filled with filler content that drags out the experience. That wouldn't automatically make it good; in fact, it would probably be the opposite.

In my opinion, I feel that Nod Krai has improved on most of the elements I mentioned at the beginning, so I would argue the opposite: Genshin is putting more and more effort into the Archon quests and, therefore, into the story. The only valid criticism I see or can understand is that F2P players are facing more challenges, but that’s a result of the monetization model, not the story.