Islam and Economy

Amid the recent market crises. I heard some voices on Arabic media saying that this is the natural end for capitalism and that Islam is the right way for planning socio-economical policies. While I don't intend to defend capitalism. I do have a small question for those people: If Islam had such a great financial system embedded in its policies and teaching, Why aren't people using it? Even more: when did people use it and showed that it was successful? 1400 years ago? What proves that it will work for the current size of trading we whitness. Until these answers are given, that claim seems more like a political nostalgia rather than a credible statement.