As it is obviously something that worked in previous DOS titles, I see the reasoning to have them in this game. I like the idea that in another playthrough you get some more insight into the character, that now plays the protagonist role.
However this is a feature without benefit for me at all. I rarely do full playthroughs again and I also generally do not change my playstyle (ranged stealth) too much either, so there is little incentive to choose, say Lae'Zel. I also usually make a character sort of mirroring myself, so pre-build characters are especially problematic. For choosing one I get certain dialogue options and one deeper quest. That is definitely not enough for me to justify new playthroughs outside of my chosen character. In order to make me interested they would do something like Tyranny, where every choice I make in the game has grave consequences and significantly alters my playthrough. And even there I only played through the game once. Also, the writing of most companions right now is very poor, as is the interaction within the group, barely existant. What good is a feature when it does not significantly alter the relationships either?
So I wonder how much is really down to players being able to experience a slightly altered playthrough and if not having to mess with the character generator is not the biggest incentive of pre-made characters. So you save 5 minutes in the C-gen and get more fluff, over meticulously creating your own character that adds nothing (so far) of story value. I can see how that is the key factor here.
Optimally you would want a fleshed out experience for both the options and a form of interaction within the group so that you do not get the feeling the additions of Origin characters is irrelevant and that you do not miss out anything but the personal POV, when playing a custom character. So far I do not see how they can deliver on even one of the approaches.