Why do we need a universal currency?

Recently we hear often, the voice to introduce a universal currency or a united nations currency as the need to maintain the stability of the stock held by most of the nations raise. Is this possible and will the united states allow its currency to be dropped or replaced as a reserve of most of the nations?

Firstly, let us analyze the cost of introducing a universal currency for reserves kept by different nations as a bail out or backup for future uncertainties. Currently USD is used as a reserve currency in many countries. This has been seriously challenged by EUR in the recent years. One of the main reasons why USA takes no initiatives to implement this at the united nations is that USD has gained a strong and stable position in the global market due to it being considered as a reserve currency by many countries of the world.

Secondly, without doubts the initiative to bring out such a currency will involve huge costs and efforts that might have to involve all the  members of the united nations. Thirdly, such a currency will replace the domination of USD over many many years.

Now let us see how a common currency will help our economies. Firstly, a stable currency will help all the countries to keep their reserves at the same exchange and avoid fluctuations. Secondly, a common currency will make it easy for taxation and movement of goods over different borders. Thirdly, investment by various countries together to avoid faking the currency.

In my opinion, even if it doesn't happen immediately, there will be a time in the future when all nations would change to a common currency for reserves forfeiting all the problems in it.