Discomfort from contradictory information.
We all have a need to know we are sane, rational and good humans. However, we have difficulty admitting we are wrong or dealing with contradictory information. These situations create an effect called cognitive dissonance.
Cognitive dissonance explains a wide variety of otherwise irrational behaviors in people. When we are more invested in a decision, product or something else, we tend to become more defensive about it. This is because we have an innate need to justify our increased commitment. This explains cult-like defenders of certain games and developers no matter what mis-steps are made. Humans just have difficulty accepting that they can both love some aspects of something and hate others. We have a built-in need to commit to a consistent sentiment.