As Jesus was training His apostles to lead the church and evangelise the world (a task that was totally unknown to them at that time), He wanted them to ask questions because He wanted to share His 'secrets' with people who would treat them preciously. Holy things are to be treated with special care (Matthew 7:6). Jesus' task was not to educate and heal a nation but to prepare a handful of men to change the world through those 'secrets'.
 
Jesus chose His men for special reasons: one to betray Him to death and the others to proclaim new life in Jesus. The training period was only about two and a half years and in that time they needed to learn to see things from God's point of view. They were not well educated (Acts 4:13) but they did learn the secrets of the kingdom because they were hungry to understand what He was saying.
 
By quoting Deuteronomy 29:4 and Jeremiah 5:21, Jesus showed that the Law and the Prophets predicated the blindness of Israel, and indeed the whole world. So He refused to throw out His pearls of truth to those who would not treasure them (Matthew 7:6): but He wanted His disciples to understand. After He had risen from the dead, the significance of all these parables came alive to them (John 2:22), and when they received the Holy Spirit they were empowered to teach others (Acts 1:8).
 
Some people today like to be amused, intrigued or even educated by the words of Jesus, but few are hungry to understand the secrets of His kingdom. The Bible is a mystery to people who scoff at it; although the Holy Spirit will open vaults of priceless treasure to those who desire to know God. Do not be surprised that when you are hungry for more, the Lord will let you see more. So ask Him to open your eyes to see the secrets of His kingdom (Psalm 119:18); and learn to be obedient to Him ... as you are, He will show you more.