Why John never mentions the Transfiguration

Why does John, who was an eyewitness of the Transfiguration of Jesus, never mention it in his gospel, letters or the Revelation?

John, Peter and James, all did glimpse Jesus' glory in the Transfiguration. The fact that John does not report it may be, as Eusebius suggests, due to his desire not to repeat stories from the already extant Synoptic Gospels.  This is speculation, and quite reasonable.

But we are here for *interpretation*, not speculation.  John indeed says, **"We have seen His glory"** yet does not mention the Transfiguration.  Still, in his Gospel John speaks very much of Jesus' glory.  It is a dominant theme, in fact, beginning in 1:14. 

In 2:11, after the miracle of the wine at Cana, John summarizes: 

"This beginning of signs Jesus did in Cana of Galilee, and manifested His glory; and His disciples believed in Him."**

 This miracle was practically invisible do all but those who put in the water and drew out the wine (the servants).  And only really his disciples saw and put their faith in him.  Yet, in John's eyes, it was Jesus manifestation of His glory.  Jesus' hiding His miracle to all but those who obeyed Him was glory.  This doesn't make sense ... if one has a wrong hermeneutic.

In ch.12 He also speaks of glory following his words to the Greek believers about the kernel of wheat, "Shall I say, `Father, save me from this hour?' But for this purpose I came. Father, glorify Your name."  This "hour" was the moment of Jesus' ultimate glorification.  He says it again in 13:31f: "Now the Son of Man is glorified, and God is glorified in Him. And ... will glorify Him immediately."

Again he speaks of God's glory in 14:13, 15:8, 16:14. In ch.17:1-5, He says:

“Father, the hour has come. Glorify Your Son, that Your Son also may glorify You, as You have given Him authority over all flesh, that He should give eternal life to as many as You have given Him. And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent. I have glorified You on the earth. I have finished the work which You have given Me to do. And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was."

John does not explain why he omitted the Transfiguration. But the fact that he does, while repeating Jesus' words of glorification pointing to the cross, suggests what Martin Luther described as the "Theology of the Cross" as opposed to the "Theology of Glory".  The latter easily enthralls the natural man; the former is perceived only by the mature Christian, and only in the Gospel.

We need a biblical hermeneutic if we would truly discern the message God has given us in the Bible.  Inasmuch as one's hermeneutic starts with his presuppositions, the theology of the cross, versus the theology of glory, is one that would take its force from John's gospel. 

Sadly, Christians today seem enamored of glory and are ignoring the cross as the real manifestation of God's glory, and thus, also as our destiny.  This may be the root and source of dispensationalism, since it is a hermeneutical framework that dismisses the spiritual meaning of the church (que kingdom of God) and fixates solely on the material kingdom.  Futurist prophesy thrills, and sells.  So it is the majority view.  But I could be wrong.