New story, new origin characters. The origin characters are part of the appeal--genericized player-made characters won't feel as gripping. There's a reason basically
nobody talks about "Tav", but lots of folks talk about the Dark Urge, and it ain't because the latter's
daGiant in the Playground Forumsrk, it's because there's an actual character to them.
Self-insert characters are fine, but it's a damn sight harder to build a compelling game with
only such characters playable.
Or, if you prefer? There's a reason most people don't play "I created five characters and my GM friend runs for me". We want to see, hear, and explore the stories of things
outside ourselves. In the CRPG world, that means created characters.
It can still be a BG game and not be set in Baldur's Gate. BG2 and Throne of Bhaal don't take place anywhere near Baldur's Gate, so it's not without precedent.
Yep. Athkatla is about 320 miles south of Baldur's Gate. Hell, most of BG3 itself occurs at a fair distance from the city--first you're on a nautiloid in Hell, then you're crashed on the beach, then pushing through the Underdark, then passing through the shadow-cursed lands. Sure, Act 3 is the biggest act and has tons of stuff to it, but for being called "Baldur's Gate 3", you spend less than half the game actually in/near the city.
Sometimes, the name of a franchise outlives the context that started it.