You can currently play with a custom party through some multiplayer shenenigans. It's also been stated that you'll be able to create a whole custom party in the character creation screen. You'll also be able to recruit generic customizable mercenaries later on.
I'm against the ability to mess with companion builds, though. They're established characters and their features define them, especially class and background. (Their ability score distribution could be tweaked, though...)
As little as I like the origin characters. . .I agree.
