Why not have a list of options at character creation like Neverwinter Online? Let players pick where their character is from and at least some sort of basic background based on the background they chose.
Probably because this will create a cartesian product of possible dialogue options. It was implemented in NWN2 OC (I definitely remember some NPCs reacting to my background with unique lines), but considering that all dialogues in BG3 are voiced, Larian might not even have considered this, realising how much additional work will be required. it's definitely a railroading, but I can't really blame them for that.
