You'll never have the kind of ability to shape your own character in a crpg than you would have with a flesh and blood DM, there's only ever going to be a fixed amount of choices the game will be able to work around, so from my perspective having a character with so many variables already defined by the game works out to a more satisfying experience.
I don't think you'll have your hands tied by playing a character with an origin, it won't be narrative handicapped by a backstory, the experience is already handicapped, it's just a matter of how much they put into giving agency to your character and an impact to the choices they make, and because every companion can be the POV, how each divergent choice for each of them will impact the main narrative and every other character. If that doesn't sound interesting to you what does?
DOS:II didn't really do that for me, but I neither did I ever get the impression that it was a priority for that game, I do think it's something people are going to come to a Baldur's Gate game for, it remains to be seen how adroitly they deal with it.
