Blessings and Cursings (Deuteronomy 28)

"I call heaven and earth to record this day against you, that I have set before you life and death, blessing and cursing: therefore choose life, that both thou and thy seed may live." (Deuteronomy 30:19) 

God reveals in His Word a human being is blessed for obedience and cursed for disobedience.  

"With my soul have I desired thee in the night; yea, with my spirit within me will I seek thee early: for when thy judgments are in the earth, the inhabitants of the world will learn righteousness." (Isaiah 26:9) 

"The earth mourneth and fadeth away, the world languisheth and fadeth away, the haughty people of the earth do languish. The earth also is defiled under the inhabitants thereof; because they have transgressed the laws, changed the ordinance, broken the everlasting covenant." (Isaiah 24:4-5) 

Why does God curse or punish us for disobedience?