To Judge is to form opinions after observing reality. Prejudice is to form an opinion before making an observation.
The distinction of what's important to you is determined through judgement. We must discern to give meaning to something. To live by the principle "I shall not judge" weakens our ability to discern. When everything is given equal value, life can seem arbitrary and meaningless.
What's better is to not let judgement determine your decision. To avoid arrogance when we judge and accept the reality that we know far less than we think we do about what we judge.
Where we direct our effort is a result of the judgements we make.
Judgement of oneself by others is often seen as a form of criticism. Those who avoid criticism will limit themselves.
I believe many of the issues we face today are the result of limiting our conversations to 180 characters.