Well, if you think about how you feel when reading John or Matthew or the born again Mark (don’t be persuaded by those who say otherwise: no one can write as Mark wrote except that the Spirit of God, of Christ, of the Father, dwells in him with the infused light of Grace, received in Baptism, his new birth into the Kingdom of God) - if you think about what is going on inside you when your read these books, you feel like you are knowing Jesus personally when you read John. John is your friend and bishop, letting you know your friend Jesus.
The other writers are instead letting you look in on Jesus from the outside and letting you see as an outsider how Jesus acts and overhear him talking with his disciples.
When you are done reading them, your appetite is awakened to wish that you also could be walking with him like his disciples. You hear the parables because that is what outsiders hear; but you also are peeking in on Jesus explaining plainly to the twelve. After reading these gospels, you want to go and find Jesus to join him; you want to be with him and know all things plainly like the twelve… But where can you find him? Then you remember reading that he sent his disciples with authority and power to speak for him, to make disciples (authority and power to grant the Holy Spirit and citizenship in the Kingdom and new Birth by baptizing and by teaching all whom they baptize), so you seek these twelve apostles, or you seek one whom they have appointed before they died. That is why you come to the Church - the successors to the twelve are here to unite you to Jesus whom you want to be with after reading the other three gospels. [This is the work of Gratuitous Grace]
The Synoptic Gospels awaken your desire to be with Jesus, so you seek union with him. John, then, is teaching you all about the one you are united with, so you know him, where he is from (the Father), and so you know who you now are after you were baptized (in the world, but not of the world). [This is enlightening you with Sanctifying Grace to where you begin to know your new life and begin to live it - doing all your doings virtuously]