Perhaps the reason, besides the many offered by Theologians and Bible commentaries, Job chose to 'bless' God in spite of the many trials and tribulations that come his way, is that every time he received something from God, his focus was not on the thing in itself. He saw that merely as a by product of God's continued assurance that He was on his side. So rather than take pride in the 'by product' Job's eyes were set on God the real gift. Hence when all these so-called 'gifts' were taken away from him, he was never really perturbed. His assurance was firm: God was with him (perhaps more than him being with God). Suppose God Himself were to have questioned his fidelity and love, that would have been the end of Job... but that was not to be.
Most of us, on the other hand, want more. We ask for something and when God assures us that what we already have is plenty, we do not listen. When out of His generosity, He grants us something, we say a casual 'thanks' and before long, ask for more. Like the camel and the Sheikh who were travelling in the desert. At night when it started raining, the Sheikh was in the tent and the camel outside. The camel asked the Sheikh to let it just put its head inside. The tent was a small one, but the Sheikh agreed. Soon the camel asked permission to put in its neck too. The Sheikh consented. Then it was the hump and a while later, the camel was in the tent and the Sheikh outside in the rain!!
We are so full of God's bounty but without God; not because He wants to be away, but because we put Him aside (or outside) and keep His gifts near at hand... who knows which of the gifts we need at what time!