I personally don't think the wording of the AMA is conclusive enough to be reassuring. They speak on actions being the most important part of the world reacting to you, but never speak about uniqueness of story between origins and custom characters. In other words, it sounds like "trust us, it's better than dos2" but without any concrete examples as to how. I am sure it feels a bit better, but I'm wondering in what ways it actually is.
I agree, and that's why I have that "if" at the end of my post. This is something I also will need to see for myself before I am fully satisfied.
I fear that custom characters will boil down to "Blank Slate Character ### Class/Race/Background, Voice 3 of 6, Male." Meanwhile, every origin gets to have a tailored experience, and you could have chosen to be one of them, even if you were really hoping to get a full experience as a custom roleplay character. I know this point has been beaten to death, but it's incredibly important to my enjoyment of the game. I'm sure I'm not the only one with a similar feeling.
I share this feeling with you in a huge way.