It feels like an attempt to straddle the two kinds of RPG's we've seen over the last decade;
On the one side you've got Mass Effect and the Witcher series, where you have a main character that very much has their own identity and story.
On the other you've got Baldurs Gate 1/2, Dragon Age 1, where you're character is a blank slate to be filled in.
I think both styles of games can be enjoyable, but I do recognise you're making some pretty big compromises in story telling to put BOTH into the same game.
I think they're spreading themselves a little thin to be honest. It's going to be hard to try and make easy of the playthroughs unique and interesting.
They tried to some extent with DoS2, with each character having a few unique dialogue options and quest events that set them apart, but I never felt much desire to play the game from their point of view. In fact, a lot of the personality and character was often stripped away when the player took control of the characters.
I understand what they're trying to achieve, but yeah.. I think it's a very ambitious feature and difficult to do well without spreading yourself thin.
This is also where I stand on it. I enjoy both kinds of games but prefer blank slate protags for my RPGs. In theory, I don't have a problem with Origin characters but when I played D:OS 2 I kept feeling like having both kinds of protags present just limited everything. And so I fear it will be the same with BG3. Game development only has so many resources. I just feel like trying to make sure all of the Origin characters have their custom options and content is going to detract from the custom player experience.
But, I would like to be proven wrong. And with how much development has gone into the Origin system already, with the voice acting and coding that dataminers can find, it's not like it's going to go away. I've accepted that it's a done deal. So all that's left for the devs is to do a good job :P