A unified currency backed by a unified political power is no way to stabilize it. If you want to have any attributes, then I'm afraid it is datong.
The world is very complex, not only economic activities, human society as well as political, military, cultural, religious...... And so many activities, and different, not all human society problems can be reduced to economic problems. From a purely economic point of view, perhaps a single currency has many benefits, but from the perspective of human society, the single currency is a disaster.
Could you expand more on this?
Not that I'm disagreeing totally with you on this particular point, I just want to hear your substantiated opinion on it. I have no doubts that single currency would be a better option economically, but I don't quite see the logic behind claiming that such a currency per se should necessarily be a disaster for human society (or just bad for it). Personally, I can't come up with anything which could justify this point of view (apart from issues not directly stemming from currency existence as such), but maybe I'm just missing something in the bigger picture