Is it desirable to use unique currency and coins across the planet?

Question

What are the socioeconomic disadvantages?

I mean "same currency".

Answer 1

Don't know about the entire planet, but, as far as the Eurozone is concerned, it helps to have a single currency (the Euro), as it makes cross-border trade a lot easier to figure, plus it's far easier for tourists to need only one currency if they travel through various of the European countries that now use the Euro.

One of the disadvantages to a single currency is that countries lose their ability to defend their own currency, which is kind of tied to their own national identity. For example, the Deutsche Mark (DM) used to be a very strong currency backed by a strong Central Bank, but now with the introduction of the Euro the DM has disappeared, and the nation of Germany has lost a strong identifying characteristic of their culture and country. (They still have really good beer, though.....)