‘ In those days there was no king in Israel, every man did what was right in his own eyes.'
Here is now the reason for their questionable behaviour. It was because in Israel every man did what was right in his own eyes. This in the writer's view was the sad state of things. The first stress here was that the people were lawless and acknowledged no one over them. They did what they wanted and they ignored their true King Who was Yahweh (Deuteronomy 33:5). They did not submit to His kingship or seek to know His laws. So it was their attitude of heart which was in question, not the lack of One to rule over them. Because of this they were not submissive to the central sanctuary and to the covenant and to the religious authorities appointed by Him. The theocracy was failing because of the unresponsiveness of the people. And this was seen as illustrated by Micah.
Perhaps, however, it also had in mind the coming ideal king as depicted in Deuteronomy 17:14-15, who would not multiply wives to himself, but would sit on his throne and study Yahweh's Laws and keep them. Such a king was not here as yet, for there was clearly no one to guide Israel in the way of truth. To make this phrase simply a comparison with and justification of the monarchy is just too glib and pedantic. The writer has earlier made quite clear his views on that kind of monarchy in, for example, chapter 9. It may, however, have been a wistful look forward to when such an ideal king as is described in Deuteronomy might come. This might suggest that it was written when such a king was theoretically still in prospect in the time of Samuel, without having been marred by the reality.