I wont argue that 4 is somehow better than 6 as the people who want a six man party ..want a six man party...my views are:
1. If you love BG1&2 and that is your benchmark then you need to potentially view this as a whole new D&D game as Larian Studios are not trying to make BG3 in the same literal sense as 1&2. This is their game,20 year later & you can just see how much it means to them & how much effort is going into the game - watch panel from hell. 2. I stopped playing D&D 15-20 years ago but from what I can tell 5E is designed for a 4 party crew - Solaster seems to be doing the same thing. 3. Yes the game will of course use some of Larian studios IP but to say its just a re-skin is nonsense - do they have unlimited funds..no..they do have 300+ people (who they are paying salaries to) working on the game - they cannot do everything, I think Sven mentioned limitations on a couple of occasions during the latest discussion. 4. Absolutely its D&D everything they are doing is trying to bring 5E rules as closely as they can (& in a format that works for video gaming) it has a massive D&D vibe - you cant say it has any other, its a D&D game plain & simple. 5. It may not be in EA but multi classing is coming to the game 4 party members can realistically play as more than 4 (well give you more variants & play styles) & at level 10 max you wont overly penalise your character build (now im going back a long time here but as I recall multi classing could be weaker at higher levels - not so much earlier on...but alot of fun to play).
