Why should the Muslims accept US$, which is worth nothing but a piece of paper?

Asslama o Alaykum, Why should the Muslims accept US$, which is worth nothing but a piece of paper? According to original Bretton Woods monetary agreement signed by all the countries in 1944, all US dollars would be redeemed for gold on demand at the rate of $35 dollars per ounce. on August 15th, 1971, President Nixon simply ceased redeeming dollars with gold, at any price. The Bretton Woods arrangement clearly stipulated that dollars would serve as Central Bank reserves as good as gold. Since 1971 onwards all the world is accepting US dollars which is worth nothing more than a piece of paper. I would refer to one article at www.plata.com.mx/plata/plata/worldres.htm which is sufficient to explain in detail the complete situation. My simple question is: Are the Muslims still allowed to accept green paper called US dollars?