What is the point of Camus' including a chapter of this sort -- one in which we are introduced to several of Meursault's friends and acquaintances?

Introducing the reader to Meursault's friends gives us a keener insight into how Merusault's mind works. We've already seen the relationship he had with his mother, his inability to grieve, and his lack of emotion. In meeting his friends, we come to have a better insight to his self-imposed isolation, his lack of feeling and empathy, and his disconnection from others.