Here’s a few off-hand. Minthara. Ludicrously ‘evil’, and unbelievably in-your-face about it. I don’t have quotes, but think back on the scene – she really pushes the comic-book evil persona.
I disagree, and I suspect you haven't seen as much of her character as there is to offer.
If you go the "romance" route with Minthara, you have the opportunity to connect with her and see into her thoughts. Within, there's an expression of fear and vulnerability. It gives you a new insight into her character.
The illithids. The ‘bad guys’ are the overly evil illithids you encounter everywhere. No attempt to disguise it.
For all we know there are multiple factions of illithids pursuing varying agendas, some of which could certainly be more nuanced than you're giving them credit for.
Then the ‘good illithid’ (the guy in the underdark) is too ‘good’ – he’s too ‘pure’. That’s blandly black and white.
I can't help but feel like you're jumping to conclusions based on your own bias. In other words, you seem to expect a certain level of writing and thus fill in a lot of blanks.
The illithid in question once partnered with a lich, offering the undead creature souls while it took the brains. Even now, the illithid has to satisfy his appetite, and though he searches for a solution, he still eats the brains of living, sentient creatures. This is a conflict in his character that is, in my opinion, undeniably interesting.
It’s been a while since I played it, but the red hobgoblin and Minthara and the goblins have very, from what I remember, one-sided ‘evil’ motivations for assaulting the druids.
They are searching for the weapon that the Absolute has commanded them to find. I can see players joining them in an attempt to get closer to the cult and find out more from within. I can even see some of the characters, like Astarion, joining them because they are embracing the powers offered by the Absolute. For Astarion, after all, those powers mean freedom from his former master.
The writing is so forgettable that I can’t remember what the druids are about.
I dare say a lot of folks don't remember Shakespeare from school, but that doesn't exactly make it bad writing.
But Halsin is an overly virtuous – noble, infallible, mallet-over-the-head good guy.
Again, I don't think you're looking too deeply into the story and considering what's going on around the edges. I suspect, for instance, that Halsin may be partially responsible for what happened with Ketheric Thorm and the Shadow Cursed lands. Which he is now trying to put right by joining whatever group he can, whether that be the player characters or Aradin's Beno Boys.
I think there’s some ‘dark druids’ or something in the grove as well, but from what I recall they’re so patently ‘evil’ as well that there’s no nuance to it.
To my understanding, the Shadow Druids are a group that believe the growth of society harms nature. Cities and cutting down trees and so on.
In the case of BG3, the Shadow Druids specifically warned Kagha of the armies coming... the drow and the goblins and the gnolls... and told Kagha that the best way to protect the grove was to use the Rite of Thorns, to seal the grove off from the coming darkness and bloodshed. That's why she's acting the way she is: to protect her people.
