Why is it so hard to adapt VNs into anime in a way that captures the feeling of the original?
i think there's two main reasons
it's similar to the difficulty in adapting any novel, that being that the freedom of pure text, or in this case, text with sparse visuals, leaves a lot to the audience, while adaptation naturally removes such ambiguity. it will never fully align with how people manage it, and things will always need to be left out
most VNs are multi-route, and you can't adapt that easily. unless you're literally Fate/stay night, no production committee is going to commit to multiple different adaptations for each route right away, so there needs to be compromise. frequently, that means choosing one core route to adapt, while including details from the others. however, for fans of the original, it will feel like that core route was handled poorly, and any details brought up are merely misused
a good vn adaptation isn't impossible, but it's pretty difficult, and it really can feel like the two mediums are at odds with each other