What if I end up finding a member annoying and obnoxious?
I think that's why we get a chapter to explore them. Like many here I am fine with it - I prefer to choose my party as stay with it. Swapping, equipping and managing characters I don't use outside required quests is just detium. Ideally game is about choices and game reacting to it, and hopefully our choice of companions will be impactful as well - in skill and tools at our disposals but story beats NPC reactions and narratives archs as well.
Another question is, if it is necessary. It all depends if they have something cool in mind for characters who won't join you. In D:OS2 they were mostly unexistend outside one story beat - if BG3 would expand on it (like a lot lot) that could be cool.
But it's only a chapter. Is it that the characters don't develop at all after the first chapter? What about the potential of party balance? Does that just not matter and I'm stuck with obnoxious characters because otherwise I'd have 3 rogues and a wizard? It paints the player into a corner. I'm not sure I agree or understand when you say that the game is about choices when this is clearly something that removes a lot of that choice and flexibility. I'm fine with the party size being smaller, but with the fewer companions in general and now we're locked into just 3 of them after the first act... I dunno, that worries me.
And yeah it's potentially a story reason. I suppose it's all a matter of wait and see.
What makes you think characters won’t develop after the first chapter? There is no evidence to indicate that.
You will have something like 20 to 30 hours to get to know your party members and find ones you like. If there is a gap in the party composition, 5E is very flexible, and with a multiclassing you could probably make any combination work.
I agree that 20-30 hours is a decent time to get to know a companion. However, that assumes that I'm spending all the time with only the 3 that I have chosen to spend time with from the very beginning and that I haven't experimented with anyone else.
I would expect the characters to change. In fact, that's my point. If this is the case, couldn't a character grow old and wear me down with their personality after awhile? What if we clash? What about conflicts with other characters like I had mentioned before? Will there simply be no major conflicts after the first act? Also, will there not be any new characters after the first act? That seems somewhat limiting and disappointing to me.
The story is making it out to sound like this is a desperate situation - surely this would change people, and would lead to depth in characters that I think we all would want to see. Is that depth not there?
One thing I liked about the original games it that there was a lot of depth in your companions. They could, for example, disagree with how you led the party and choose to leave. I thought that was a simple but effective way that helped to make your choices more meaningful. Does that not happen, if after the 1st act you're stuck with your main 3?
You make a good point about multiclassing. I've never played 5E.
