There are other reasons also why the Lord used parables. He was protecting his timetable. He had come to spend approximately three years teaching the people, teaching his disciples, proclaiming a way of repentance and forgiveness, but at the end of those three years he was going to Calvary's cross. On that cross he would be the representative of all those who in their lifetime would be brought to repentance and faith in him. He would bear away, the eternal weight of punishment due to them for their sin, and God the Father would lay upon him, as he hung and suffered on Calvary, an invisible punishment, the punishment due to all those who he would save, and he would bear it away. That great day, that great accomplishment, that terrible and yet wonderful act, the atoning death of Christ, was what he had ultimately come for. To live a life of perfect righteousness, and then to suffer and to die to make an atonement for sin. But if the message of salvation had been preached in the meantime as openly and plainly as it possibly could be, there would be universal revulsion; there would be fierce opposition and attacks. The problem was that these scribes and Pharisees were intensely self-righteous people, and they were determined not to be influenced by anything Christ would say. They did not want this message of salvation, they were offended at the idea that they must humble themselves before God, and pray to him for forgiveness, and depend upon his method and his way of bringing that forgiveness to them. There were attacks upon Christ, and against the disciples, but they would grow and mount. So to protect the program of the Lord, the gospel was preached very largely through analogies, parables, to preserve Christ and the disciples until he was ready to lay down his life.
But also, as previously mentioned (Mark 4:1-2), preachers today can use parables to soften the edge of the gospel. Parables have an ongoing value, because they are, when explained, tremendous illustrations of the way of salvation.