Firstly, we do believe that all authority comes from God, just as we believe all life comes God. We refer to God as all-powerful meaning not only can he do anything but also that all legitimate power finds its source in God.
Once a leader understands that, then they also understand why the Book of Wisdom refers to them as "ministers of his kingdom." In many cultures they still refer to officials as ministers (i.e the prime minister). Every kingdom is "HIS kingdom" because HE (forgive the sexist language ) created it all.
Imagine for a moment if every leader from the President to the parents of every family saw their power and leadership through the lens of ministry. If they realized that they were excising a kind of delegated power only, how different our world would be.
The Book of Wisdom is not reinforcing some right of the King to have people bow down in his presence. On the contrary it reads:
though you were ministers of his kingdom, you judged not rightly,
and did not keep the law,
nor walk according to the will of God,
Terribly and swiftly shall he come against you,
because judgment is stern for the exalted-
For the lowly may be pardoned out of mercy
Many of us exercise some kind of leadership or have some authority, even if it is over nothing more than the dog. The reading reminds us that ever time we exercise authority we should remember that we do it with an eye toward the source, doing always and only what God would have us do.