The problem with a lot of games that claim to be replayable is that you usually have all the information after one playthrough, the only thing that makes a second playthrough of a game really meaningful is if you don't get all the information about the story just from playing through it the first time. Just having a point near the end where you get to choose between three endings isn't it, but only getting three distinct endings based on what you accomplished during the first two acts is.
If all the questions of Baldur's Gate 3 are answered after one playthrough then there isn't much incentive to go back in, that goes for the companions and for the main plot.
Well, it might warrant two runs at the least, what with there being options to either side with the Absolute or not. Add on top what unique racial reactivity there might also be (I highly doubt they'll just drop the framework they can carry over from D:OS2 where being an undead gave you quite a few unique opportunities to pursue). And playing as the different origin characters, unless the drop the origins altogether (which I would personally very much welcome, so that they instead focus on letting custom characters have a lot more room to play around, while the origin-specific dialogue can still be seen if you were to switch to said characters during conversations when you have them as companions).
I disagree on that having "all the information" makes the second playthrough meaningless, though - if a game is very well-written, then going in again after having seen the plot unfold allows you to pick up on the foreshadowing and the nuances of the writing, and look at things from an enlightened angle.
