How much the purchase power of currency affects prosperity?

It seems that there is no end to the monetary policy easing.  According to the Wall Street Journal’s article published on 5 February, 2013, French President F Hollande is calling the euro-zone governments to consider the monetary zone’s policy on foreign exchange. The massive quantitative-easing programmes launched by the US Federal Reserve and the Bank of England as well as policies of the Bank of Japan to keep yen at law rates encourage European leaders to respond with similar decisions. However, how effective is monetary policy easing?

The threat of undermined stability of the global financial system was the main reason for central banks to start purchasing toxic assets and injecting additional cash into the system. Initiated cooperation was seen as essential to calm the markets; however, quantitative easing programs have grown into the permanent policies. Moreover, the necessity of such prolonged actions is backed with the economic recovery policies. The financial stability was sustained in exchange of currency devaluation policies those were also understood as favourable circumstances for exporters. The race for better export conditions sparked currency wars between the major advanced economies; however, does reduced purchase power of currency increase the prosperity?  

Money is a short term asset and the value of the securities denominated in particular currency also fluctuates according to the exchange rate. Thus, how much wealth is generated through the policies those reduce value of currencies?

Maybe it depends on goals and measures those are placed in action. Could it be that the devaluation of the currency is a goal and the monetary easing programmes are the measures to support the devaluation? Could it be that increased export is a goal and the devaluated currency is a measure to achieve it? Perhaps all of those measures are used as undoubted believes of strong recovery. But how much reduced purchase power of currency increases consumption and strengthens consumers’ ability to choose products and services?

So, if the goal is prosperity, could the devaluation of the currency be the right measure to pursue?