Since monetary policy is implemented through the financial system, this system should be as efficient as possible in order to guarantee the smooth and effective transmission of monetary policy throughout the euro area. The degree of financial integration is therefore important in determining how effectively this transmission will work in practice.
Taken to the extreme, this line of argument leads to a view of the world most famously associated with some Austrian economists. Good times are always setting us up for the next disaster. It is not clear to me what the appropriate policy response should be to this. Certainly one should always remain alert to the possible dangers.