Uhm yea I think the point you guys are making about origin characters needing to be more 'streamlined' (at least in the beginning) than the companions recruited later on makes sense. Although I do still think there was more depth to origin characters at the very beginning in act 1 of D:OS2, maybe it's because they moved around in the map rather than standing stationary at camp like they do in BG3. Then again, I do think D:OS2 is the best RPG ever made so I am biased. I have not played the other games you mentioned because they didn't seem to be fully voiced which is a must for me.
As to why Halsin and Minthara are exclusive - this is pretty much the reactivity to consequence of saving/destroying grove. They are hostile companions, like Edwin/Minsc in BG1.
Regarding this, the way to recruit both of them prior to patch 1, was by not destroying the grove and not killing Minthara. As a result, in that particular scenario they had even less reason to hate eachother.
As for romancability of companions, it makes me sad that we don't have dwarf, halfling, gnome and goblin companions. I feel sorry for players who pick a short person as their main character and not having a fellow person of similar stature to be happy with...
