Yeah, this "Let's just give everyone money and everyone can be rich!" doesn't work in real life. Money doesn't always equal wealth, you know..
Actually it is production that creates wealth and production is stimulated by consumption.
When world currency would be deflationary then consumption will slow because everyone will be motivated to hold onto their money, not to use it on consumption. That in turn means that production will slow down and that actually means less wealth to everyone.
Now, if the globe would be in one peaceful society, then maybe it could fly. Less consumption would mean less destroying our natural enviroment and all. But because evolution dictates the survival of the fittest, this laziness propagating economic way won't work. People who work more and better will always rule over those who just want to sit on their ass.
There is a logical fallacy in assuming a rise in value of a currency and a shrinking economy. If nobody would spend money because of a rising value of money, that money would - in the end - buy less again because the economy is not growing but shrinking. Of course, this is a contradiction. No such thing will happen. Instead, an equilibrium will exists that indeed differs from our current system.
Nobody will hoard money indefinitely. There is a simple reason for this: time.
Nobody lives forever, right?