There are 8 Origins Characters. (I believe this was announced somewhere, though I don't have the source.) That's not a lot indeed.
I would very much want to see 4-5 standard companions. Not Origin (i.e. playable as PC, infected by a tadpole), just normal people who you can travel and adventure with. Also, people with more casual, "humane", down-to-earth backstories. No need for a grand quest. They are not meant to be main characters, and hence should be much less costly to write for and develop than OCs.
BG2 had 17 companions (if you count ToB). I doubt BG3 could reach that number, but 12-13 would be great.
One other thing these additional companions would be great for is replayability. With just 8 companions, I can have seen pretty much there is to see about everyone in 2-3 playthroughs (I don't care for the extra content you can see by playing as an OC instead of just with an OC, and the banter between pairs of companions is secondary to the relationship between the PC and the companions).
