So you want to evade to a NATO discussion? Not helpful. And the power of germany relative to the other european countries can't be compared to the power of he US rewlative to other NATO countries. German gdp is the size of France and Belgium or France and the Netherlands. Not so long ago, US gdp was as big as the gdp of all other NATO members combined. I hope I don't have to speak about the disparities in military spending, power etc.

And that bigger countries have somewhat more influence is normal. Germany is more powerful in the eurozone then Estonia. But so is Belgium.

Legal obligations: Well yes. A matter of interpretation mostly. What is price stability, after all? 1%,2%,  3% inflation? Fighting deflation? I won't say the governing council of the ECB can just do what they want. But they have considerable space within the legal mandate. They just don't want to use it.  

And instead of critiquing the ECB or thinking about how this can be changed, you seek out a national scapegoat, letting right-wingers in all other european countries off scot-free. Neoliberalism is awesome, if just the evil germans wouldn't ruin anything.