The problem with why Job, at least to those who don't blindly follow/read it, is that it doesn't "fit" with a lot of the rest of the bible.
The reason for this, is that the STORY is much more ancient in origin, than the other books of the bible. The story itself states that Job was an "oriental", which is quite different than the other characters of the old testament and their Jewish origins.
The book of Job was quite obviously " added ", by the religious leaders, and most likely to be a fear inducing lesson to keep the sheeple on their toes. What is a better " group control", than making the sheeple think that at ANY time God can just come and wipeout your whole family, and life, all on a whim.
The book of Job is archaic in origin, and story, and message. It existed far before the bible was first written, and was added in, as almost an afterthought, but a good one, at least from the religious leaders perspective, to keep control of the people.
This is why, when WE read it now, being fully awake and away from the mind control Cult, it appears CRAZY, and PSYCHOTIC. It is NOT a story of a loving God. It is the story of whimsical, indifferent Gods, who think NOTHING of using humans as mere playthings. Humans, in the story of Job, are worthless. They can be bartered with, killed, destroyed, and tortured, for NO reason. The "lessons" in Job could have EASILY been shown without the evil toying of human life.
I can recall an Elder from a visiting congregation, giving the talk one Sunday, and he was saying how wonderful the book of Job was. He continued to say how fortunate Job will be in the new system, because he will have 2 sets of children to welcome back in the resurrection. STUPIDITY at its WORST!!!