'Constructive ambiguity' is a prerequisite of political utterance. Changing your tune is rarely politically advantageous. For the German ruling parties it was essential to maintain their stance towards 'Greek' debt or suffer a major shift in strength between the right of the grand coalition and the social democrats (with behind them their potential coalition allies in any administration of the centre-left). But the world of 2010 and its political needs is long gone; the language that 2010 world needed for German interests and coping with German fears is rigidly inappropriate; to get that language toned-down has taken too much and far too long - from the exit of inadequate political actors (the members of the IMF 'team' were hopelessly under-qualified for what they were doing, indeed even for what they thought they were doing) to the exit of governments.
Any competent economist can state how to deal with 'Greek' debt, within a eurozone framework and without disturbing treaties; indeed a whole range of means can be offered (and are readily available within the gloriously constructive ambiguities of those treaties.) It's not the economics of it all that's defective: it's over-defined political statement masquerading as (under-defined) political stance and objectives. Still, austerity and its associated utterances has been gagged if not yet bound at last Friday's meeting, of itself a considerable achievement.