David Clines argues that the conclusion of Job is that retributive justice is not a necessary part of God’s creation:

From Deconstructing the Book of Job:

Where then stands the philosophy asserted by the poem of 3.1–42.6, the core of the book as a whole?… This seems open to no doubt… that it is the righteous, not the wicked, who suffers; all it does is to expound it at length, dramatically and unarguably. What the poem does, philosophically speaking, is to prove over and over again that the doctrine of retribution is wrong.

Every time Job’s friends fail to carry us with them in their denunciations of Job, and every time Job excites our admiration for his injured innocence, the poem convinces us again that the doctrine of retribution is naive, dangerous, inhuman and, above all, false. If ever for a minute in the course of the dialogue we are tempted to believe that Job after all must deserve something of what he suffers, or if for a moment we find it hard to believe that anyone can possibly be so blameless as Job is making himself out to be, the affirmations of both the narrator and God in the prologue stride forward in our memory: there is none like him on earth.

From Coming to a Theological Conclusion: The Case of the Book of Job:

…From a more intellectual point of view, we might say that the divine speeches have refused the categories of the dialogues, and in particular the complaints of Job that the world is not being governed with justice. What they have left in their place is the suggestion that God does not put himself forward as world governor, and that his acts toward his creation are not to be judged in the scales of justice.

From Seven Interesting Things about the Epilogue of Job:

The question is: How can what Job has spoken about Yhwh be called “right”? Much of what Job has spoken about Yhwh has been abuse and criticism of the deity, and Yhwh himself has typified Job’s speeches as “darkening”. Yhwh’s “design”, that is, his principles for the structure of the universe, and has criticized Job for speaking “words without knowledge” (38:2). Carol Newsom, for one, speaks of the “impossibility of harmonizing v. 7 with the preceding material in chaps. 3:1–42:6.”

Yhwh, we must accept, cannot be referring to Job’s initial speech of acceptance after his calamities have fallen upon him: “Yhwh has given and Yhwh has taken. May Yhwh’s name be blessed” (1:21). For the deity plainly knows about the friends’ speeches (“you have not spoken the truth about me,” v. 7), and therefore must be aware of Job’s own hostile speeches also, which rather cancel out Job’s docile first speech. Nor is Yhwh likely to be referring to Job’s short responses in 40:4-5 and 42:2-6, since they are surely too insubstantial to outweigh the criticisms Job has earlier made of Yhwh.

The only thing about Job’s speeches that Yhwh can be approving of is Job’s denial that Yhwh governs the world on a principle of retributive justice. For Job, it was a criticism of Yhwh that he did not keep days of assize, judgment days when he would mete out punishment to wrongdoers (24:1). For Yhwh, the whole of his speeches from the tempest (chaps. 38– 41) implicitly deny that retribution for good or bad behaviour is a feature of the design of the world order. Yhwh’s own depiction of his purpose for the universe emphasizes sustenance of its life forms, the non-human creation being a very prominent part of his concerns, rather than a micro-management of human beings. Job’s complaints about God’s failure to manage the universe have paradoxically put their finger upon a fundamental truth about Yhwh, that such is not his interest.

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The important point here is that the [Hebrew] is not behaviour attributed to the friends, but behaviour that Yhwh says he may engage in if he is not appeased by Job’s prayer. It is the outrageous behaviour of a person whose anger is out of control. It is noteworthy that v. 7 has said that Yhwh’s anger has burned hot against Eliphaz and the other friends. This is the only place in the book where Yhwh is said to be angry. Though Job has inferred Yhwh’s anger from his experience of him (14:13; 16:9; 19:11), the only time we have seen anger is when Elihu becomes angry with impatience at the inability to refute Job adequately (32:2, 3, 5). Yhwh is angry here for the first and only time.

The anger of Yhwh, his demand for an enormous sacrifice, and his threat of outrageous behaviour all cohere. We are meant to sense that the friends’ imposition of the principle of retributive justice upon Yhwh’s dealings with the world is regarded by him as a terrible affront, and a tragic misunderstanding about the divine design for the world. If Job has been “darkening” the design (42:3), they have been doing worse: their arguments seem to have been bent on destroying it.

In an unguarded moment, Yhwh lets slip that he feels in danger of behaving badly, outrageously in fact, but he knows how he can bring himself under control: a pious person can intercede with him on behalf of those who have aroused his anger. Then he will calm down.