It's actually perfectly possible to make that work. See BG2 Jaheira and the Harpers incident. If you play a certain way, Jaheira WILL join the fight against you (And given her skill selection in THAT fight, this can be absolutely crippling too, especially when you do that quest late-game). Attack children on the street, and the paladin will openly attack you right then and there.
My point for bringing this up, the huge exposition dump this kind of design requires (select companions "front-loaded" at the beginning of the game) aside, is that I don't see how the game can be immersive when I travel as a "group" but every single character acts as a standalone entity. In BG2, when your *party leader* gained entry, the *party* was allowed in. This is why you call BG a "party based CRPG"
And this is what confuses the heck out of me. Are we playing a PARTY of people, 1 designed by us, up to 3 chosen at the start as companions. Or are we playing a mob of 4 people who we have to talk with 4 different times in every dialog ?
Or better put. Are companions actually integrated as part of the party, do they banter amongst themselves? Or are they just traveling along, but technically they are all stand-alone puppets who might at certain trigger points do X no matter how the travels, dialogs etc went?