Every country has it's own needs and wants, because every country is different. Some countries are more poverty stricken than others. Some countries are more populated than others. Some countries contain more diseases than others. Again, all countries are different and therefore require different things.

Think about it: if one government rule came over the entire world, then how do they decide what to focus on first? Do National Governments need to report to this new overruling Government? For one Government to try and take action in one particular country will leave others deprived. If this Government acts on its own, then how could it possibly hope to make a positive difference?

Next question: how do we choose who represents this government? That is basically choosing a President of Earth, and will be full of naught but biased and cultural votes. Every country will want their culture standing at the head of this Government, which will lead to many conflicts between Nations. However, if we chose not to have one individual represent this Government, but rather a certain amount of people (I.E one from every country), then wouldn't that be basically the same as the United Nations? We couldn't turn around and say that this "group" of representatives can be all from one country, because again, we would run into similar problems to those made by an election towards a President of Earth. Suppose that if there were a president of Earth, and an American became President, wouldn't that outrage other countries? Imagine the conflict resulting from that!

A Global Government Organization would be a foolish creation, because there would be too many resulting conflicts with too much pressure because of too many problems worldwide. We should allow National Governments to continue to work within their country, and allow the UN to solve the worldwide problems that currently, and will later in life, exist.