So why do people even play an RPG if they are so uninterested in the story that they would respec a "Daughter of Darkness" into Light domain lol.

Why do companions need to be optimized in the first place?

I just hope Larian aren't going to be half-assing the companion builds simply because "you can respec" and "we can't please everyone". Like she probably shouldn't have that Fire Bolt cantrip but Minor Illusion or Chill Touch instead. If she would turn out to be a brainwashed Selunite or something, having the Light or Dancing Lights cantrip would be a nice clue. But Fire Bolt just seems very unrelated to everything, plus she can already use a Crossbow at range with her 14 Dex.