Aside for any personal preference, a sudden realization just hit me a couple of hours ago while checking the "six-men mod" (which is actually more a save edit than a proper mod).
Why is Larian NOT taking advantage of the fact that this is an Early Access build, precisely to give us an option at the beginning of a new game to pick between the "standard and supported" party of 4 and an "experimental and unstable" six characters mode"? No rebalance or tweaking of any sort required. Just that, an experimental option.
That would give them a chance to see what people choose, what they tend to stick with, how much they enjoy it, etc. All through client-integrated telemetry. Isn't that what a EA is supposed to be about? Or is it more that they just can't be bothered to try it regardless of what people want, at some point?
I'm starting to wonder that myself. When they announced BG3 for EA I though Larian did that because they genuinely wanted player feedback abut game mechanics, rules interpretation and impelentation and stuff like that. But it now seems that they just wanted people in the EA to test out pure technical issues.