Children not only need to hear our conclusions (Do this! Do that!) they need to know the thought process that got us to those conclusions (Here's why you should do this or that). They need context. If you only offer orders and rules, then we are not teaching, not serving them as parents. We are just pontificating.
It's hard work articulating why we believe what we believe. We may hesitate, out of fear, to tell our children the honest "whys." Perhaps if we share, they will discover our secret weaknesses or find flaws in our reasoning. But rather than hiding our imperfections, if we let them know we are fallible as they are, we share with them a common bond and a true honesty. Rather than just trying to pour truth into their heads, we can help them make the marvelous discovery that they have something to contribute to our lives as well. We are fellow struggles, learning how to live right in a confusing and challenging world.