Yeah, no one believes Larian's speech that a custom character will have an equal experience
TBH I would rather see "origin stories" instead of origin characters.
1)This way you might have side quests for companions designed not twice but once( they will always be a companion and never a playable character).
2) If you have 4 people playing together so be it : They make their characters and choose an "origin" story for themselves.
Might be a bit harder to come up with the stories since you don't know the " protagonist" gender, look , allegiance or class. Come to think of it it's probably a stupide idea. Or one requiring A LOT of imagination.