Tools like Myers-Briggs are great for looking at yourself, understanding your strengths and weaknesses and learning to be a better person. However, when you start using them as weapons, the focus becomes other people's problems. I guess the benefit is you don't have to worry about self-improvement anymore when a personality typing system makes it so convenient to place the blame somewhere else.
I must admit that I do judge people harshly for several Guardian characteristics, but I realize that those characteristics are also (in many cases) strengths.