Jesus explains to us why he speaks in parables. Why... it's to confuse people so they will go to Hell, of course!
And he said unto them, Unto you it is given to know the mystery of the kingdom of God: but unto them that are without, all these things are done in parables:
That seeing they may see, and not perceive; and hearing they may hear, and not understand; lest at any time they should be converted, and their sins should be forgiven them.
Jesus Christ... what a prick.