I'm going to be a dissenting voice here. I LIKE the idea of creating a single character and having other, fixed companions with their own points of view and reactions. I am not interested in role-playing versus myself - I wasn't in D:OS 1, so much so that I didn't play D:OS 1 on release - I waited until the AI personalities were added before playing for the first time.
I do not mind that I won't have the opportunity to customize my entire party, and that they will have their own distinct roles and strengths. It just means that I can focus on tailoring MY character in a specific way.
However, I'm a bit less certain on the AI companions never leave or attack. That really depends a lot on the specifics, though, and I have no idea what those are yet. It could be good, it could be bad. I don't want to be forced to take a spy for the Divine Magisters with us in our party, but other than that, it probably doesn't matter so much.
This. To me making the player create the whole party is just lazy on the developer. Granted, I think it should be an option for those that just want to make some meta-team to blow through the game with. But I want to find some NPC companions and have to learn about them in game, see if we 'click' or not, determine if I want to do any personal quests for them or not, etc.