Corruption is relative based on what is codified in law, so when corruption occurs, we see what needs reform in society. Reform can come in the form of paradigm shift or a change in policy. Everything that is illegal is corrupt, but not everything that is corrupt is illegal. Corruption is merely anything outside the established social norm.
Corruption erodes public trust. Once a corrupt element is uncovered, it takes a lot to earn trust back after a betrayal of those served is made known. Corruption may be a good temporary solution to a nagging problem, but in the long run there is no good that can come from a betrayal of the public's trust that our officials are looking out for the common good.
Among the definitions of corruption are the degradation of moral values and other standards. It is the opposite of integrity. Corruption has led to many complications in many governments, in ways that make things harder for everyone else. An honest policy and lack of selfishness is a better approach to government, not corruption and greed.