Nah, even during Early Access Minthara was never portrayed as a genocidal evil maniac, but the Absolute's slave who becomes caring, compassionate and terribly conflicted when the artefact temporarily breaks her domination during that celebration night. Here's my comment about her romance even back then during Early Access where we were discussing the "evil" path;

"I found her romance to be very sweet, especially with her wishing to take us as a consort to Menzoberranzan and belonging to each other for eternity."

To which The Red Queen replied that our definitions of sweet wildly differ grin

But I was honestly not wrong, because Minthara is incredibly beautiful with her charming personality, full of unconditional love and devotion, loyal to the very end and in awe with the main character. She is the only companion who ENTIRELY has the player's back no matter what after she's rescued. And even while she's half-controlled by the Absolute, she tries to kill the main character peacefully in their sleep so they don't feel pain.

Larian also had plenty of other detailed aspects about Minthara that were never included, including the fact that she would get pregnant and all companions (including Karlach calling her Minthy and wanting to be the child's godmother) would comment about it. So she was not only always intended to be a companion, her content was so much more fulfilling and not even clashing against having Karlach if legitimately recruited.

But Larian clearly rushed the game, cut corners, merged some storylines to "make sense" and by doing so left her entire side to gather dust just like Karlach and Wyll got ruined for release. Karlach and Wyll's early access stories were SO MUCH BETTER than what we got, because Karlach in particular had business in Baldur's Gate due to Zariel and her lackeys, while Wyll was rushing to save Mizora from the Absolute. The full release Karlach however is just... a virgin romance simulator and Wyll is Wyll.

Minthara is simply a victim of Larian rushing and having no freaking idea what they're doing with her, which is still going on 7 months after release.