The answer to this question has huge implications worldwide as the risk of sovereign debt default has never been higher.
It appears they want to be able to change the rules if they think they need to. Even including bank depositors.
In a ground breaking case that has MAJOR potential ramifications on the legality of future bail-ins in the US, the US Supreme Court has ruled in favor of some hedge funds that will be paid the full value of the debt they owned (Argentina debt).
While this ruling only applies to bond holders, it might apply as a precedent to any future default situation.