I understand that we have different preferences and it is fine, my wish would be to have more unique dungeons in the next games.
I normally love things like that in games. I read everything and there's not a game I own that I don't have a 100% in. In Skyrim it's barely even storytelling.
My experience with Skyrim did lead me to developing strategies for other games, after having less time, but at the time I definitely went about it in one of the longest ways possible.
It's probably time for a replay.
The game I had too much time to play was Gothic for me, this one has no quest markers and I also had no internet so I had to struggle with it but I still have it burned in my memory.
Now I started maybe 1 year ago a new game on SE, just essential mods for me because I had the bad luck of my game crashing in certain regions of the map when I was around level 30 and I had to give up on the save. I was using those cool mods that improve the cities with new buildings, NPCs and quest. I could not solve that issue and I promised myself that I will play next time only with minimum stuff.
I suggest to ask in winegaming subreddit for more info on what other players are using and what to avoid. If you have both games try them both , no mods and compare how it looks and feels.
FNV did that way better - but okay, FNV did everything better.
There are a lot of issues with Skyrim, there are some very funny videos about it, but for me personally those quirks are not significant enough to complain.
But that's just it: They don't add lore, they add noise. If this kind of story telling is done well and occasionally, then players would actually read those letters. You are right, here they don't, and that's not surprising if they are placed everywhere.