I've been playing with a 3 custom character party and I think I see why Larian is doing it the way they have it now. Each proper player character (not companion) has its own answers/progression stored. So all 3 'player' can have the same dialogs with the party NPCs (also reputation for each player/npc combination is kept separated).
This would mean jumping in the middle would most likely cause some serious issues for how their system works, as the paths to an answer would be missing in the saves - which is problematic.
On the other hand they already have it that some dialogs with quest NPCs are unique and thus shared between all party members - in this case it shouldn't be a big issue to switch (just my guess)?
For me personally the biggest problem with this current state is that knowledge skills within the party seem to be ignored. For example my ranger has low charisma but arcana as skill. My paladin is the face but the party doesn't profit from the ranger actually knowing something - he basically doesn't listen when the paladin is talking and can't pick up info or share it
This leads to having to use characters that are both the face of the party and have as many skills as possible (hi bards), while others are just for the environment interactions.
