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.
Of course they know. They just don't care and think we are in the wrong. It's funny because if it was a matter of "what the majority prefers" it was incredibly easy to put it to the test: just add the option early in the EA process and track data of what most players would go for. We suggested this and they didn't do it.
Same with the chain system to control the full party: it's terrible and one of the most widely unpopular things I've ever seen in any game, but somehow they are absolutely adamant even in the face of overwhelming evidence that there's something good there.