America has laws and these laws are voted on and passed by the people for the benefit of all. While we may not agree with all laws, and sometimes law enforcement may not apply these laws fairly or with the best wisdom, it nevertheless has an important duty to protecting citizens from crime, corruption, and predatory commerce. At the essential root of all economic systems is trust and law enforcement helps to ensure that people trust the system.
Independence means that law enforcement should not be at the whim of any politician or entity that could potentially skew the protections its affords its citizens. While judges have an obligation to interpret the will of the people, and often times hit a butterfly with a hammer, it is ultimately the people who have passed these laws that should have the final say.
While we may not see this at first look, law enforcement protects the value of the dollar and the economy. Each economic system is based in trust of trade and trust in the value of the dollar. When countries become corrupt it has a detrimental effect on the value of lawful commerce and causes wider devaluation of currency. The end result is the disintegration of values, economic activity, and beneficial citizen behaviors.
With skewed application of laws people lose a sense of belief in the overall American principle that if someone works hard they will receive rewards through entrepreneurial and personal initiative in the market. The system will look "rigged" and people will have less qualms about violating the law themselves in order to give themselves opportunities. The rich, poor, and popular should all be subject to the same laws.
Law enforcement has a sacred duty to protect the entire economic and political system through a balanced, independent, and thoughtful approach to the application of law. While there are many good reasons to reform law enforcement to ensure that justice is not blind to its own misapplication it should nevertheless be partially insulated from interference. Enough protections to keep it fair and unbiased while at the same time ensuring it doesn't run wild without accountability.