Ironically being 'judgmental' means we're no longer open to making an open-minded judgment, we have preconceptions and are no longer curious and open to learning. There's a clear difference between being judgmental and making a judgment; we can't sit on the fence the whole time, we'd be good for nothing if we weren't able to make a decision based on informed opinion and our heartfelt values (rather than assumption or prejudice). But even then, we do best to keep an open mind.
Why would you not be open to alternatives? Because of attachment. Like Buddha said, attachment is the cause of suffering. The real you is not attached, and you can find the real you by recognizing the loving aspect of your self, that which is non-judgmental and compassionate. That's you.
Getting the picture, rather than agreeing or disagreeing, liking or not liking. Then, uninfluenced by fears, responding consciously rather than reacting.