Having completed 7 full playthroughs (rather a lot, yes I know), here are my thoughts on origin characters played as main characters:
Having seen them as proper characters beforehand, as the main character they come off as lobotomized and soulless by comparison. Losing their voice acting and animated dialog severely hurts them. As they stand, Dark Urge excluded, they're not really worth playing as a main character. If anything they're a direct downgrade from the same origin character as a follower. So you only lose out on something by choosing them - not to mention they can't even be customized whatsoever.
It does make one realize just how much the main character is hurt by not having voice acting and animated dialog as such, and just how much more they could be if they did.
I realize it'd be quite an expense and will likely never happen at this point. But I must recommend it all the same.
Agreed completely on the not worth playing as origin companions imo. Even DOS2, people say "you're missing out on so much" and then only when pressed do they admit "well, you get more nuance and a bit more lore from playing as an origin", and DOS2 pushed origin companions more than BG3. In BG3 I see almost no benefit, the main story doesn't change at all, at most you get a few slightly different cutscenes and some dialogue options to change the flavour of the game.
I'd actually argue that Dark Urge is the most unique playthrough simply because of the unique mechanics, so if you absolutely wanted a totally different playthrough DU would be where it's at.
