Just like The Devil Wears Prada, having characters talk and share information with each other — in this case, about Rose’s parents — creates a sense of expectation/anticipation around meeting them.  

From this conversation, in any scenes with Rose’s parents, as a reader or audience, we look for signs of racism or lack thereof, which puts us in an engaged and active position. 

It also helps us to contemplate the nature of racism, which is the underlying theme of the movie.