I personally only plan on playing multiplayer, and I would hate for 3/4 of my party to be forced to play one out of a set of premade characters instead of their own character, and I am certain I am far from alone with this opinion. The option for each player to create their own character definitely needs to be there.
On the other side of the spectrum, I can absolutely see how getting companions with unknown motives instead of a whole team that you designed yourself would make the singleplayer experience more enjoyable (unless you're REALLY into roleplaying), so that option is surely needed as well.
I think a good solution could be to ask, at the character creation step, how many characters you want to create (or in the multiplayer case, ask each player if they want to create their character), and then just fill in the "non-created" slots with companion NPCs. That way, should a player want to control a pre-made character in multiplayer, they can, and should a player want to design their entire team in singleplayer, that's also a possibility. Everybody wins.
