Swen talked about it in Panel From Hell. They intended to make backgrounds impactful, but after some time realized it would require some very specific background. He brought up an example of a writer asking "ok, but how did the character become a Folk Hero? What kind of Folk Hero? What was the character's heroic deed?" or something along the lines. I'm as bummed about backgrounds not mattering for the story as everyone else, but I do see their point here. They'd need to shoehorn custom characters into very specific backstories for dialogue options to make sense and not feel suspiciously broad. And most people would probably prefer their characters to have exactly the stories they've made for them and not be forced into a background they might dislike. So for example: they'd have to make you a Noble of a specific family to be able to create a compelling story/dialogue around it. And at this point it's getting close to DA:O-style origins, a lot of work and, as I mentioned, becomes limiting freedom in backstory. "Custom" and "reactive" don't play particularly nice together, unfortunately.
Though I suppose they could make it... vestigial/low-key but present? It would still be nice. Like being able to make a pompous answer as a Noble, express being uneasy in a city as an Outlander or mention familiarity with hard life on the streets as an Urchin. Small, generic stuff, but still a bit of background acknowledgement.
They aren't putting that level of attention into like, alternate dialogue things for your class, they're just little optional fluff conversation options, so it feels a bit weird to hold backgrounds to a MUCH higher standard and then give up on reaching that point.
