She was Lolth sworn, doesn't take away her self reflection and neutral character traits after freeing her. She has great "redemption arc" qualities. She is not good, neither is Astarion. A lot of people don't like they don't have an option to save her while being good. You can alse save Khaga, and she is pretty evil.
The people who want to play evil do it for the sake of playing evil, Minthara is just a bonus. Many play evil only to get Minthara and would love to have more options in an rpg to safe her. You can see it by the many comments in the internet, reddit posts, discord etc. Consequences are great if you are given an amount of options, but in this case it's just black and white while you have a lot more options to decide the fate of other characters. This feels forced.
Right now the evil path is like a sidekick experience compared to the way the game was supposed to be played (not being stupid evil) It's great for those who want that experience, bitter for those who like her character.
So you are always forced to go evil if you want her, but you can immediately jump on the good path after recruiting her and she doesn't mind (it feels very natural to have her on a neutral run). If Wyll and Karlach leave you after doing something really evil, why doesn't Minthara leave you when you do something really good? Atypical for an exclusive evil character. So it would make sense to have her on a neutral playthrough as well. Sadly the community seems to be really split on this topic because of the way she is portrayed. Most will keep seeing her as the crazy evil goblin leader, not her beautiful character which is locked behind this path.
If you like consequences and exclusivity so much, then Karlach and Wyll should be exclusive as well. His Patron wants to kill her, so there should be consequences if you choose either side. But you have the option to save both. Shadowheart and Lae zel should be exclusive as well, no? They even try to kill each other if you dont convince them. But you have the option to save both.
