It really didn't have to turn out like this. After a couple of years the internal discussions will leak out, and we'll get a better sense of why the current government led by (and consisting entirely of) the Greek Socialist Party pushed these draconian neoliberal reforms (liberal as in as in classical liberal, not American librulz) on the country. The only justifiable reason I see is that the leadership of the party thinks that they can't pull off a switch to a "new Drachma" because it would be impossible to keep it a secret long enough to implement the change successfully. But I don't believe that will turn out to be the real reason, or at least the main one.
Update 2011.06.30: An article from the BBC explains why Greece can't default as long as it continues to use the Euro. As long as the primary budget - the budget minus interest payments - is unbalanced, default is not possible because the Greek government is depending on more loans of Euros to pay its employees and vendors for the foreseeable future. The neoliberal economic organizations that are pushing the austerity package on Greece in exchange for the loans are projecting sufficient positive economic growth to bring the budget into surplus, when coupled with spending cutbacks. But as we've seen in the UK, cutting government spending (demand) when there is insufficient private demand to make up for the cuts leads to economic contraction. It's a vicious circle: cuts lead to slowdown which reduces revenue which increases the deficit which leads to more cuts. So the latest package just another kick at the can.