The problems in Greece were not caused by the credit crisis. Sooner or later Greece's model of government spending without a solid tax regime would have collapsed, the crisis only made the underlying problems more apparent.
Without the Euro, the greek central bank could have increased inflation and downvalued the Drachma, so the government could spend, spend, spend. This was the Modus Operandi before the Euro.
I don't say, that this is a responsible way of managing a countrys finances, but if the alternative is increasing infant mortality and extreme unemployment for almost a decade, I can't see whats so bad about that.
I certainly agree with the MO of inflation in Greece pre euro. I'm not sure about the real unemployment situation, but I only know about a few islands, not the mainland. There a lot of people work cash in hand in the tourist trade, they are technically unemployed (and their businesses pay very little in taxation as most of the money isn't declared)
Greece should never have been allowed into the euro in the first place. The EU is essential for Greeks, many of whom have gone to other parts of the EU to work, just like Americans left Detroit after 2008.
Italy's problems are a bit similar to Greece's but their economy is just a lot stronger. In Spain it was clearly the inflated housing market that caused the problems.
Italy is like two countries - the North has a strong economy, the South seems to have mainly agriculture, unemployment and mafia. Think of any famous Italian brand (or look at any Italian machinery), it's probably from north of Rome.