Here we are indeed forced together(For now?!).
Well, perhaps strongly encouraged together, given that we don't need to join up with anyone as far as I'm aware

. Though I personally find it almost impossible to pass a potential companion by.
And even if we do join up, we might even in EA find that the reasons for staying together become too weak, as Wyll and Gale might leave us depending on our actions at the grove, and of course we can send Astarion on his way after he reveals his true nature. Maybe SH, too, after she tells us she's a Sharran?
I definitely agree, though, that we're likely to see there being more factors that could drive the party apart, as well as bring (some of them) closer together as the game progresses.
And now I'm going off topic in the thread I'd split out because it was off topic elsewhere! Sorry, stopping now

.