OM(F)G, this thread fills me with dread. I certainly hope that BG3 will not turn out to be fan service for waifu-worshipping incels. The way romances are currently handled in EA is not great, which adds to the fear.
That being said, Minthara could be made into a fine party member for evil MCs. But there already is a cleric that seems compatible with all kinds of good/neutral/evil playthroughs. Maybe joining the Absolute (if that kind of play-through/choice is possible) will alienate almost all party members (except Astarion, maybe?) and Minthara will replace Shadowheart in that case...
You know, people just enjoy the character, there's nothing wrong with that.