I'm not qualified to judge whether Piketty is correct but I can offer this analogy. In the past, when I have loaned money to friends and family, my attitude was "kiss the money goodbye". If the money was spent wisely and served a useful purpose, I was happy. It's nice to get repaid, but it's not essential.
Here's the problem: Merkel can't politically justify to give Greece more german taxpayer money because it isn't spent wisely. After 5 years of crisis, Greece still has a primary deficit, while maintaining more extensive welfare programs than most EU Members. Even in the case of debt forgiveness, they would still have a massive household deficit and be in the same situation again soon. So it's not about getting money…
Greece had a primary surplus in 2014.
http://finance.yahoo.com/news/greece-revises-down-2014-prima...
> while maintaining more extensive welfare programs than most EU Members.
What extensive welfare programs would that be? The 12 months of unemployment insurance? They don't even have a means-tested program to ensure a subsistence minimum for people younger than 45 years!
http://www.keepeek.com/Digital-Asset-Management/oecd/governa...