However I maintain that not being able to talk with Asterion about Baldur's Gate is a massive missed opportunity that I hope gets ammended by the time of full release.
What would Astarion have to say, really? Depending on how honest he is, he either remembers very little of his mortal life, or wouldn't want to discuss it because it'd paint him in a terrible light. As a spawn, he was only let outside to lure people to Cazador's dinner table. So what is there in terms of conversation? Which taverns are best to pick up strangers at?
Shadowheart is too missing a lot of her memories. Only Wyll seems like he'd be up for a chat, but then another problem: what would you have to talk about? Baldur's Gate is not a small city, and Wyll is a noble turned Flaming Fist turned local celebrity. Maybe if you're a noble or another hero you'll have some shared experiences to talk about, and those I think will get some acknowledgement once the background tags are properly implemented. But what would he have to say to an urchin or a guild artisan? You're in completely different social circles, walking completely different paths in life, and have completely different experiences of the city.
I don't know, maybe it's just me, but if I meet someone from the same city while travelling, the place itself will be a conversation starter at best.
It'd be good if companions asked you about yourself though. All too often in these games it's you interrogating everybody else, and never the other way around. I want to know everyone's history, why don't the others want to know mine? PoE did a little bit of that in the beginning, and it was very nice to flesh out my character's background beyond the option at character creation.