I personally don't really care if we have a party size of 4 or 6 for strictly combat balancing reasons, even if I would prefer the latter because it'd expand party compositions considerably.
But at the same time, I can understand where the party of 6 crowd comes from if they are arguing from a party interaction/writing standpoint, because larger parties means greater importance on dialogue that makes the whole party feel like they're alive in a way. A party of 4 indirectly diminishes the need for it.
I will also bring up yet again that if we end up losing like half our cast of playable characters largely due to an arbitrary headcount limit at the end of act 1 once more, I don't think people are going to give Larian a pass for that this time. Larian learned the wrong lessons from D:OS2's success if they think that had anything to do with the success of that game, when it was largely successful DESPITE that.