Fiscal Differences Come Home to Roost

The creation of the euro was also aimed at generating a single monetary policy, lowering transaction costs, keeping inflation comfortably low and avoiding competitive currency devaluations.

Instead of taking the next step of a fiscal union where taxing and spending policies would fall under central control, eurozone creators substituted little-enforced rules on the size of member countries' debt and deficits.

"It is a failure because it was not followed by the necessary fiscal union. A currency union is a long-shot without a fiscal union," Cam Harvey, a finance professor at Duke University, said in an email.

These rules, spelled out in the Maatricht Treaty, were badly broken -- even by fiscally-conservative Germany.

"They didn't live up to their own rules fiscally and it has now come back to haunt them," said Sylla.

Even if the rules were followed, Harvey said most of the benefits of integration came through the "harmonization of regulations via" the European Union -- not from the creation of the euro.