‘ In those days there was no king in Israel. Every man did what was right in his own eyes.'
The writer was clearly disillusioned. Even in this matter of Benjamin the people had stooped to subterfuge and hypocrisy, not seeking Yahweh's voice when they had the final difficult decisions to make. From Judges 21:4 onwards there had been no consultation of Yahweh. They had done what was right in their own eyes without looking to Yahweh as King. What they had done as a confederacy had been on His behalf, and yet when it came to the crunch they had ignored Him. Once again it was apparent that there was no King in Israel, neither divine nor human.
And that was the continual problem. They just would not give Yahweh His true place. Central government was loose, the central sanctuary was marginalised, justice was left to the clan, who tended to favour their own, God's law was only applied as seemed fit to them (Judges 19:1 on). And individuals went their own way in matters of religion (Judges 17:5-6). That was not how God had intended it to be.
There are, however, those who claim that the writer is writing in order to recommend kingship in Israel. But can that really be so? Could the man who demonstrated the final failure of Gideon through multiplying wives as a result of his princeship (Judges 8:30), who described the rule of kings as being like a tree waving its branches aimlessly over other trees (Judges 9:9; Judges 9:11; Judges 9:13), be finishing off with a panegyric to kingship? Was he not rather longing for the true application of the kingl rule of God, for his people to turn to Yahweh and really treat Him as king?
We can contrast with all this the change that took place when Samuel became priest at the central sanctuary. Then Yahweh was acknowledged as King and Israel prospered. There was a King in Israel and men did what was right in His eyes. And all the problems slipped away. It was not the system that was at fault but those who ran it. So what was he trying to do? He was trying to wake Israel up to its need to respond to the Kingly Rule of God. He was preaching a message that would not be preached again for a thousand years when another would come proclaiming the Kingly Rule of God.
So it may well be that this book was written by Samuel, for he too protested against earthly kingship. He too warned of the dangers of appointing an earthly king who would simply prove to be like Gideon and Abimelech (1 Samuel 8:10-18). He too recommended trust in the Kingly Rule of God. And when the people sought a king like the nations no one was more against it than Samuel, except perhaps for Yahweh.