It's part of human nature to categorize. I don't think so. Categorizing is very helpful to us, else we would not have evolved with that way of thinking. The challenge seems to lie in recognizing when it is helpful, and when it is potentially limiting or dangerous. Categorizing is most helpful when a person encounters a situation about which she knows very little, or must rely on information from others.
Most individuals watch others as they leave, in order to know what's appropriate.
When a person interacts with someone of an unfamiliar background or occupation, she generally acts on what she thinks such individuals might be interested in - say, a statistician is probably interested in numbers, and therefore might enjoy gambling. Going with such hunches is typically a safe strategy at first, but as she comes to know the person better, it becomes smarter to base her interaction on the information she learns about the person, rather than the group-based generalities. Indeed, an individual is likely to get upset if he thinks he's being treated as a stereotype instead of a person. Part of human nature is also to break beyond categories and traditional ways of seeing things, to create new perspectives and revolutionary approaches to problems. This unbridled creativity is the hallmark of human advancement.