Playing BG3 should feel like you're reading an epic fantasy novel. Unfortunately, BG3 has some elements which makes me feel like I'm reading a fairy tale. So, I think that at least these elements should be removed from the game:
Talking to animals and corpses
I have read a lot of fantasy novels, and none of them has a main character who talks to all the animals and corpses he sees. This mechanic gives the game a comedic element, but it takes away epicness from the world and the story.
Witch in a cabin
This storyline is directly from fairy tales, and it should not be part of an epic fantasy story. The biggest problem is that the witch is an empty stereotype, who hurts people because she is evil. Turn her into a sorceress, who has a real background and motives. Also, she should not be completely evil.
You are aware of that a lot of fantasy novels contains elements of what you call "fairy tales", right? What you might deem appropriate in a fantasy novel might not be ideal or appropriate for another person/player.
I play all RPGs with the same mindset - I use them as an alternative to reading fantasy novels (which I do... A LOT), and I don't think BG3 has failed in that perspective, quite the opposite.
Using your own examples: a hag in the swamp is a bit stereotypical, sure. But where's the harm in that? I loved that part, especially singe my ranger had unique responses that I felt was really appropriate to the situation.
And talking to animals... Like, uhm... Lord of the Rings, one of the most famous fantasy serie of all times contain characters that can talk to animals - like Radagast. If it is appropriate for your character (which is decided by no one else but the player), then what is the issue? :x
Just because something might be common in "fairy tales", doesn't mean that is out of place in a fantasy novel. <.< I mean, if we are gonna get REALLY technical, "fairy tales" per definition is just short stories made up from difference aspects of folk lore. Almost all fantasy novels are also, at least partly, inspired by folk lore ... :x