Sorry, but your title is wrong: fun is very subjective. At moment I don't like many games, though I found them fun once and may play them again. They can feel fun once again. State of mind, mood, focus, and so on, not like I can explain it why, but a bit of many factors.
I'm not a "fan" of DnD, or Larian or BG series, though played a few, and some parts were fun. So it's not a "white knight" telling you that you are wrong again: DnD isn't "bad in video game format". Recently I played Solasta, and I enjoyed it a lot, mainly because their very customizable difficulty settings - from almost God mode level very easy to extremely difficult, so the hit and miss and such details can be custom fit to what each of us desire, to allow most fun. While I played all DnD games mainly for the story, the dice system wasn't the reason to consider them annoying, but the difficulty settings (which can be solved with cheats and mods in some) or the puzzle on top of puzzle that can't be skipped or made easier, or the story "forcing" you to do things you don't like, and so on.
As someone who loves stories and RPG, I can't agree that BG3 storytelling is "mediocre". I quite enjoyed it, though I played only the early access part so far, but can't wait for the rest.
I'm not saying BG3 EA had a perfect start, there are many things I don't like:
1. the UI is worse than in any RPG I ever played, time consuming to do basic things and difficult to position your party properly, or move them
2. the character customization may seem best ever in an DnD, but sadly is very limited and can't make something I like (there's no ugly and beautiful, rather all mediocre, but of course, this is just my subjective view)
3. after I played it, I will miss the Solasta level difficulty options in every game, BG3 included
I could go on, but I just wanted to give a few examples.
These are just my opinions of course. The game could still be a fun experience to many, despite anything we think -- or could be a disappointment, especially because the BG3 title sets the expectations high. But I still have hopes that the game will be okay. Larian puts a lot of love in making it right, though they rarely listen to anyone from outside their team, so there is the risk of echo chamber effect. They have the EA feedback, but somehow looks like they won't or can't use it to change much -- or they do it in secret.
