The Lord is specifically pointing out that he speaks to us in different ways. Moses had a particular purpose that he was to accomplish. The Lord chose to speak to him face to face on Mount Sinai. But the Lord points out that he speaks to His prophets in dark sayings , dreams and visions. Even in the New Testament, Jesus spoke to the disciples and others in parables.
Parables are much like dreams.
They needed to be interpreted. Jesus is still speaking to us in parables today. However, those of us that are called to the mysteries of the kingdom can know and interpret the parables we receive from the Lord in the form of a dream, trance or vision. Those that are not believers do not understand as well as cannot understand the language of the Spirit. We as kings and priests need to search out all of the golden nuggets that contained in the Word of God.