Just think about it, a coin In your pocket with Stalin, Mayo, Kim Jong Il, Lincoln. Or the image of the Beast. A one world currency is a bad idea. Every country would loose it's uniqueness with its coins that identifies it's self and honors it's leaders good or bad.
I look at this as a significant religious step for a "One world Order" This would help set the stage for a supreme world leader that would control all global economics and eventually everything "The Beast."
Even if you are not religious would you want some Chump in a foreign country deciding that you don't need all of the 401K or Social Security that you paid into the last 40 years. That someone somewhere else needs it more. Or new taxes are demanded from you to support some BS in a foreign land that has nothing to do with you, or would never benefit you or the USA, Canada, or even Iran just because whoever said so.