Maybe, but they might be holding the six man party back as suprise for when the game is released. I'm pretty sure Larian knows that a good number of us want to play with a larger party.
This is still my hope. Of course I'd rather they did it before EA was concluded, but if the game launches with 6 I'd give them a nod.
Being able to create a custom party of 6 would also be great.
I'd like to choose party formations, and also have a solo driving cam view for non combat movement and exploration.