Why parables? The twelve disciples inquire of Jesus as to why his teaching methods involved parables (v. 10). Matthew's account implies that Jesus instructed his twelves with different, more direct, teaching methods. Otherwise, the twelve would not notice a stark difference in how Jesus instructed the crowds.
Before we can understand Jesus' parables, we must listen to Jesus' reasons for speaking in parables. His methods are for grander purposes ... purposes that non-believers outside of Jesus' circle were mostly too blind to see or too hard of hearing to understand. But we will also see what hinders most from seeing and hearing the Kingdom of Heaven.