I completely agree on your overall point, but I don't think that "good" aka "Hero" players would not want Astarion or Lae'zel in the party.
Imho their "redemption" plot is fantastic, especially for good characters.
From what I heard that might also be true for Minthara.
Minthara doesn't have a redemption plot, she's just got very compelling writing. For how little they gave her compared to the Origin characters, the quality is just as high as any of them. If only the same could be said of Act 3 Halsin.
More toward the general question of why would a good Tav bother, there's also just a TON of evidence in Act 1 that could reasonably lead any Tav, even the most extreme Lawful Good Tav, toward wanting to investigate her as the leader of the absolute's forces in the region instead of just killing her. If the ultimatum between keeping her or Halsin that made the rounds the last couple weeks made it in, that also poses a VERY fun dilemma for such an extreme Lawful Good roleplay.
