This is no mere homage or a sign of respect to an earthly King, this is religious worship. This is a confession of faith. So our Magi manifest faith! The Beginning of Wisdom is the fear of the Lord. And these Magi are well on their way from being mere Magi to being Wise Men!
You might want to remember this the next time you kneel to pray to a statue of Mary or a Saint...
It would help if people were more Biblically literate. Even Msgr. Pope would have been a little more exact if he knew he would be challenged this way by iconophobes. Searching Scripture reveals that bowing, kneeling, even prostrating, does not always indicate divine adoration (though it's related.) The Biblical vocabulary of gesture is more varied and flexible than that.
And this is something you actually know, (link), iscool, but intriguingly, have never acknowledged.