What the mayors are really saying...
We want Americans to stay and continue to prop up our economies regardless of whether there is any military necessity in their continued presence. Face it, we have not needed American soldiers for defensive reasons for over 10 years now. However, if they're pulled out of our towns, our economies will be devastated.
If there is a legitimate need for military forces in Germany, then it's up to Germany to provide them. If there's no need, then there's no need for American troops to be stationed there. They're needed much more in other parts of the world.