@SteelTempest: Not to forget Halsin and his cryptic "I am sorry, but Mystra is wrong about you, Gale." What? Why? What do you know that I don't? It's the one that confuses me most of all. All the others can still be seen as a reflection of their past break-up and as concern that the reunion might not go well, but Halsin seems to be very certain about Mystra's opinion of Gale.
I don't feel Wyll is especially tied to the main plot - only Gale, Lae'zel and Durge are baked into it, Shadowheart maybe - but it's weird that you can't even suss out what his opinion might be and maybe have to convince him away from it. Depending on what you pick, he sometimes seems to fluctuate between defender of the Sword Coast and power-grabby noble within seconds without any foreshadowing that political power might be an interest of his. I also don't think it was the best decision to have his plot get even more muddled if you recruit Karlach than if you let her die in act 1.
I think Wyll is pretty tied to the main story: he is Duke Ravenguards son, his father becomes a victim of the three Stooges, he knows Florrick and has special dialogue with her in all three instances ( four, if he breaks the pact) we meet her. We get the info about Ansur normally from his father ( never had it in a different way), Mizora , probably on Zariels orders, has a special interest in the whole affair. If I ever okay an origin, it will be Wyll - he and Durge have main character energy.
I think Shadowheart has ties to the main story in act 2, act 3 is more the resolve of her personal story. Gale has the fact, that Mystra wants the Stooges stopped and his ambition for the crown, Lae'zel has imo the most ties to the main story via her knowledge about mindflayers, Orpheus etc.
Karlach via Gortash, but that is all. Jaheira and Minsc have a personal interest in the Bhaal cult, Halsin and Astarion -I got nothing there. I think Cazador was in an early version planned as being tied to the whole plot,at least there are voice lines, where he offers us help. It might have been scratched with the scrapped idea of a plot in the upper city.
I think what I mean is: Wyll, with all I have listed above, should be tied even more, since he knows a lot of people in BG, is the ex via his father who is shown as a key figure and I'm honestly wondering why he got sidelined so much in act 3. Which is basically the point, I want to make ( sorry if it is unnecessarily complicated, I'm a bit tired and sick today and the brain isn't functioning too well:) )