Gender, race and class figure into every part of every day life. We like to think that we are not biased towards races or genders or how much money someone makes, but every time we look at someone we subconsiously, and automatically appraise them, at least to the extent of "this person is male, or this person is female", and "this person is *enter ethnicity*, or what ethnicity is this person?". We then attach our stereotypes and preferences before anything is ever said by that person. Often our opinions change after we have gotten to know that person, but as humans, we have to have a place to start.
Discussing these issues help us to identify our biases and evaluate them. We can decide if there is something we need to learn more about or confront. Sometimes the bias is against us, and we can extend our views to other people who might not understand where we are coming from.
I tend to read everything at least once without letting outside influences into what I'm reading. Inevitably, however, one or more of these issues will creep into my mind. I think about whether it is a male or female writing the piece, what sort of background they might have...