Governance is an entity which is key to any nation's survival and growth. In the democratic system it is often open to scrutiny from political opponents and the public alike; term after term members of the government face the inevitable 'threat' of being replaced during elections. Although such political diversity may seem like a threat to current ruling parties, it is essential for the nation, especially in today's democracies.
When assessing the very purpose of political diversity, one must realize that it is in fact a core component of the democratic system. What differentiates a democratic constitution from many other systems is choice, including that of one's leaders. Indeed, the freedom of choice serves as a main attraction for the democratic system. To limit political diversity such as by limiting competition and restricting the formation of political parties would be equal to removing the freedom of the people's choice. Any nation which controls the political freedom of its people to exercise choice cannot be deemed a true democracy. It is hence important for any democratic nation to have political diversity, lest if seeks to spit on the governing principles of democracy itself.
Political diversity in the form of multiple political parties is beneficial as it helps keep the government in check by ensuring that they serve the people's needs and not their own. Political diversity guarantees competition, and political competition equates to winning favour and pleasing the voters. Should such competition break down, a single ruling government can arise in the form of dictatorship which maintains power through oppression and authoritarian means. Instead of undertaking tasks to develop the nation, the dictatorship is allowed to serve its own selfish objectives at the expense of the people's freedom and living standards. In nations like North Korea and Zimbabwe, a single, self-serving government has led to low standards of living and suffering for the populace.