You are right, it doesn't fix the bug, it replaces the default targetNamespace with your choice. Note that a lot of defaults exist as variables in <ws>namespace.
The problem with wsdlpull is that there is another layer of derivation for the types which it isn't handling correctly by wsdlpull. I believe the schema is correct. One way to test is to remove the intermediate type and point directly to the global simpleType. I'm guessing, but I think that wsdlpull is interpreting the definition as empty: