I agree with Niara's point. For people who have played pen and paper D&D, the idea if premade characters is contrary to D&D game where you create and play with your own character and the story is about your own custom character.
The origin characters aren't as appealing for people who like not just D&D setting but pen and paper version. It is not just about implementing 5ed rule set, is about that playing freedom that comes from having your own character and that the story is about your character. To me, origin characters are NPC (non player characters) which should made them, by default, secondary. The story is about the PCs (player characters) who should be at the center of the action. The way they are going about the origin characters reminds me about those master with favourite NPCs that must be better at everything and always be at the center of the story to the detriment of the PCs. I didn't like it in pen and paper and didn't like it at a video game.
On the other hand, maybe Larian is going at this like an agile project and they would be adding things and making changes acording to people's feedback (I hope). This is an alfa and they might be trying to decide how to go about this part of the custom characters. And some people have offered good ideas, like the actitude that characters have in Pillars 2 or using combinations of backgrounds, races and classes to offer "stories"/Backgrounds.
I mean, the same way that Astarion label translated to "the pale elf" questline, arcstory and dialog lines, they could create 3-6 stories only selectables by custom characters that went:
"The netheresse relic"
"Betrayed by best friend"
"Criminal lord heir"
And that were related to an story arc, some quest and a few dialog lines as appropiate. That would be a middle ground. And sure, it would be more generic than what you can have on pen and paper, but basically would allow you to have some backstory. Add the option to have "none" for those who are happy with "blank/bland" slate and there you go. I mean, it is not that different from DA1, where you were each origin could be translated as a one liner and can be sumarized the same way than the origins. You can even have requisites like "only races with human ancestors, so only humans, halfelves, tieflins and similar". But you need to have at least one available for any combination of races, class and background.
Right now, I find that the origin characters are fine as NPCs, but I don't like any of the to play. And Shadow Heart reminds me too much of Lohe with all the puppet thing. In a way, I see a pattern in the origin characters offered. Like 3 males vs 2 females, one of the females posesed and one male is really undead. And the other female is somehow bloodthirsty. Funily enough, githyanky were former slaves that would do whatever it takes to not be slaves again. And that is similar to the female elf in DOS2. I mean, it is like a pattern on the origins. Not sure if intentional so they can reuse dialogs/ideas or just happened. Anyway, I rather have custom characters more developed and better integrated in the game. Also, almost everything they do to improve certain labels, like "elf" or "wizard" apply also to their precious origin characters.
The other thing that seems not quite working is to not offer something to the people who choose to not use the tadpole powers because roleplay. The people who use the power get good outcomes out of conversations and scenes. Scenes are cool, so they reward players who use the powers. Meanwhile, players who chose to not use the powers have more difficulties in conversations and get no scenes. So you penalize out of game those players. They should add different scenes for the players who chose to not use the powers to balace out the two ways of playing. At least that is my take from a dungeon master point of view. It is like that (fair) complain by people who like to play intelligent evil characters, that all the options offered to evil characters are "dumb". I mean, it is true that an evil character won't help the goblins because they get nothing from doing so. Not only they lost the help of the druid (which at that point seems like the less costly of all to get rid of the brainworm), but it is quite obvious that the absolute thing is about letting the tadpole on your brain and controlling you. Why an intelligent evil character would like to be controled and become a puppet? There is no reason. So they are "forced" to side with the neutral guys.
Balance this kind of things is difficult and takes effort. Which is why I think they are looking at the stats. Except the stats are biased, since players chose between what they are offered, and that might not show their real preffered option. Right now, they might be chosing to romance Gale, because the other options are more difficult/buggy. Anyway, I hope we would see another big patch soon and that they improve on the custom characters.