I would think that one reason in which Ali employs cultural stereotypes in her novel is to show depth of characterization. In depicting characters who initially capitulate to a stereotype, Ali is able to show their full growth and full sense of range in starting here. With a stereotype, the reader's expectations are already primed. In this, the author is able to undercut such predictions and create varied and diverse characters that challenge the presuppositions of the reader.
One can see this in the development of Nazneen and Chanu. She is shown to be the traditional woman of the subcontinent, brokered into a loveless marriage in the far off world of the West. The traditional ideas about women from the region and their condition of hopelessness are evoked. Yet, it is from this point where Ali departs and constructs a character that is vibrant and divergent. Chanu is much the same way. From a traditional man who seems to embody the essence of integrationist theory, he becomes a rather sad figure, one that only represents the blighted hopes of what could be as opposed to the stereotype that asserts selling off cultural identity for material success. In both of these characterizations, the use of the stereotype is employed to both establish reader expectations and eventually challenge them into inviting literature.
I'm writing a thesis aboutBrick Lane and i'm trying to prove that Monica Ali is using the stereotypes for a reason and not just because its "easier".