I'm pretty sure there is/is planned some sort of 'low-approval party members leave' thing planned. It's just hard to get approval low enough in EA without *Really* trying. I want to say another Chubblot video, but I think I remember it being a topic on the reddit forums too.
Anyway. I'm generally a fan of party members having more ways to express autonomy. If they don't like you killing Tiefling children, they should express that. But I'm not crazy about the generally low numbers of party members, front-loaded into act I, with zero replacements except the likelihood of zero-personality mercs like DOS2 in later acts, combined with a gameplay experience that encourages a high-party member attrition. Particularly with the Goblins vs Grove choice early in act I which is essentially a landmine placed in the path of players right in the beginning of the game, designed to remove half of your options....combined with the end of act I party member culling....not great IMO.
