I wonder if it's a sort of defense mechanism people develop. The Real World is quite crazy, and is typically governed by social rules that are fluid at the best of times, and totally incomprehensible at the worst (or for those that may lack certain social skills). Meanwhile, the fictional worlds in which we create are almost always governed by clearly defined, logical rules. If something strange happens, you just have to keep reading and it will (usually) be explained to you. Retcons notwithstanding.

I presume this is also why people are always so up in arms when something happens that contradicts the previously-established rule set.