Preconceived Notions

Human beings love to simplify. One way to simplify is to create a structure, a rule, a generalization... Some framework which would allow them to be able to explain things around them and predict future outcomes (consultants particularly love frameworks!)
And its in this love for simplification are born stereotypes... and even worse - preconcieved notions!
Why take the effort to understand complex human behaviour?
Why care about the reasons underlying a person's actions?
Why bother to observe that things change and people evolve with time?
Isn't it much easier to judge (Note: humans also love to judge) on the basis of a simplistic preconcieved notion?