Well, what do you think the purpose is of a crowning? The people already know that someone is king. The old king has died, for example. Or a new king has 'taken the sword from the stone", or has defeated a rival. King ‘de bello’ (war) or de jure (legal), king through primogeniture (birthright). . .the king is known as king. Then, as a visible sign, he receives the crown at a ceremony, is ‘vocally proclaimed’, is legally entered into a chronicle, etc.
We know Jesus is King. He would be King without any ‘sign’. But God gives us signs. We are surrounded by signs. We are signs. Part of that is because we are who we are; we are made in the image of God, who is a Sign for us as well. God doesn’t just give us a bunch of signs that lead nowhere and have no meaning. From the earliest time (prehistory) to recorded history and Scripture, to the present day and beyond, God was presenting His plan, foretelling, foreshadowing, giving signs. . .bringing to fruition, then continuing with the sign of fulfillment, the crown.
You know, if God had dropped down a big old golden crown on Jesus when He walked on earth, even in the 40 days after the resurrection, that would have had a very ‘temporal’ meaning. A king on earth (and Jesus in Scripture mentions, "My Kingdom is not here’ responding to Pilate’s questions, telling Pilate that He could have had legions of warriors if His kingdom was ONLY one on earth, or on earth alone) is not the same as a King of Heaven and Earth, a King who transcends Time and Space. Don’t you think?