Jaheira, Minsc, Viconia, Volo, Sarevok, Elminster are just too many recurring characters.
I would have expected even the storywriters to have more general knowledge of mathematical stochastics. You just have to think of the above names as coins in a common chain of events. Let's say heads = failure and tails = success for a return in BG 3, then it should be clear that never all coin tosses have the same result or show tails/success.
And also the reasoning behind this random chain is just too ridiculous:
3x humans over 100 years old and also still in their prime, two of which appear by space and time magic randomly at the same timeline and randomly in the same region. A few too many coincidences.
2x aged elves sounds a bit better, but why are Vicci and Sarevok return to BG, even though they were wanted by the Flaming Fist and should have been hunted down immediately? Sarevok in particular should have been killed after his crimes, when he should have died as an ordinary human without divinity anyway, like Imoen... And as the previous speakers have pointed out, why would he even willingly return to the place where he ultimately failed? Jaheira should have faced her own past after the Bhaalspawn saga in Thetir, especially after the loss of loved ones in BG and the surrounding areas.
Elminster making a brief appearance is the only thing that fits convincingly.
