In a true free market scenario with freely floating currencies, currencies in countries like Spain, Italy, Ireland, Greece would have devalued. Germany's currency would have strengthened. This would have made German exports (to other EU countries) much less competitive than they currently are.
However, the Euro tightly integrates these other countries with Germany and makes it very difficult for them to revive their economies.
Using a single currency without a single federal government was a risk for all countries involved. Germany has a huge interest in keeping the Euro alive and the EU as a single unit. It shouldn't be surprising that many people in other European countries expect something in return (for having given up the options that they had before the Euro)