"it is the political dimension of the EU, allowing Union-wide standards to be legislated by means of directives which become binding for the member states"

I would not say that this particular dimension has covered itself with glory of late. Whether from its lack of democratic representation, or from the actual outcomes. The level of discrepancy between neighbour states in matters such as taxation is incompatible with the smooth running of states.

And yes, a fiscal union is an absolute necessity, but I reckon that unrestricted movements of capital are a major problem even absent monetary union.

Earth provides enough to satisfy every man's need, but not every man's greed. Gandhi