My feeling about origin quests for custom characters is that it would be far too easy for them to guess wrong. For instance, my current character is a ranger who grew up working in her parents' leatherworking shop. (aka guild artisan background). It's hard for me to imagine that a generic Guild Artisan quest would fit seemlessly into her story. It seems much more likely to me that the inclusion of such a quest would feel like Larian telling me who my character is. If I wanted that, I'd play an origin character.
