I really liked that he specifically said they are designing the UI to be able to easily support someone creating a mod to increase party size to six.
Also you can rest easy for now, as good companions are intentionally withheld for now. Larian wants to corrupt their players.
Yes I noted this too in the interview. These were the two things that made me happy with that interview.
Originally Posted by DrunkPunk
Like D:OS2 I'm sure you'll be able to mod in a larger party, but just like D:OS2 it'll likely make the game completely trivial in every encounter due to the nature of the game balance.
The joy of having more companions in my party and all the attendant increase in intra-party interactions and banter as well as interactions with the world are way more important and meaningful to me than any aspect of combat. So the combat becoming trivial/non-challenging/unbalanced is a price I will happily accept for all the added fun I get from having a 6-person party.