As of the time of me posting this 403 have voted for custom character while Origin characters remain under 100.
I have to wonder if Origin characters are more popular with the casual audience, those who don't obsess over a game enough to post/vote in forums. I imagine they're probably the majority of Larian's customer base. And of course it's not like you can't play a custom character on one run and an Origin character on another - I've seen lots of people around here planning to do just that.
Maybe.. I'd personally think that these types of games would be too rule heavy and lengthy for the casual crowd though. I guess it depends on what "casual" means these days.