"This should be an additional option rather than a replacement system."
I'm 100% on board with this. My previous point about removing companion characters as playable characters was a little cheeky I'd admit. Its just outside of DOS2 it hasn't been done for (to my knowledge) and it just was a little weird to think about. I was trying to imagine myself Playing DA:O from the point of Morrigan or Mass Effect from the point of Garrus. And in my head it just doesn't work, because those games are about the main character that the player created/shaped, The Warden or Shepard. If you made Morrigan playable as the player character then you remove her interactions as a companion which seems like such a shame since I love her interactions with Alistair. I not saying it couldn't work its simply difficult for me to imagine haha.
Removal of Origin companions would be very good for the game.
The problem with the current system is that the custom character gets the least amount of content of all possible options. The origin characters also drive the main story, the same way as a custom character + get their own unique questline.
In all non-Larian RPGs the main story is driven by the custom character only and all NPCs are just along for the ride and only have their side story.