I think of the Drives/Beliefs/Heritage question as a way for players to point out something fun about their character to the rest of the table, particularly for quiet, shy or mechanically focused players. Since the players say if they earned the xp, it gives them a chance to recapitulate and reflect on the session, calling out good things and things they want to see again from themselves and each other. They might say “Hey, remember that cool flip? I did that because I grew up in the circus.” or “Remember when I totally knew all about Rendian Space Madness? I wanted to mention that I liked that and it was cool because I want to investigate space madness.” I’ve also see it work in the reverse sense, too, where some players wanted another to take experience for something, but that player didn’t want their character to be defined by that action mechanically.