Origin characters are interesting, generally better written, and fun to play. Therefore, I suggest we just scrap OP's opinion instead.
The reason origin characters are "generally better written" is that they put more effort in them. I think that the OP thinks that the work on origin characters is not finished and that if they keep prioritizing them, custom characters would be indeed worse written. Which won't be a problem if they have said so from the begining. That way, we would have known what to expect.
Now, this is EA and things aren't set in stone. They have time to put work on custom characters and level them to the same standard they want for the origins. And that might mean 5 origins instead of 10 (numbers aren't real. I've heard they would be 8
). The thing is, the OP said somethings that could be implemented for custom characters. Like using story/background labels to round up custom characters.
Zellin offered a few nice suggestions to improve custom characters. There's plenty they can do to improve them. But since resources are limited, if they only focus con Origin characters and on selling us that, well, we would get origin characters and for those who don't like to play as origins but were told that we won't have subpar experience by playing custom characters it would be disappointing. And considering that they specifically said that it won't be like DOS2 and that custom characters would be as good as origins gamewise, I would say that there is a significant amount of consumers that simply don't like origins. Otherwise they would simply promote origin characters set in stone and won't even allow custom characters. Money from the people who doesn't like origins also finance the game. Yet, significant less resources are dedicated to custom characters. Or so it seems at this point.
They could have just used the "forgotten realms" brand if it wasn't to be a BG successor and they wanted a DoS3 instead but in the forgotten realms. They would have sold anyway and no one would have got false expectations.