Remember that we have been given a narrow mandate in the Treaty to deliver euro area price stability, and that narrow mandate is what justifies our independence. Nowhere in the Treaty does it say that the ECB should set interest rates in such a way as to force policy changes on unwilling governments.
For us to do that would be undemocratic and a misuse of the independence we have been given. If anybody is to put pressure on governments to enact structural reforms, it has to be other governments within a democratically-agreed framework. Indeed, this is why the ECB has frequently called for stronger European institutions for economic policymaking.