How do I prevent JAXBElement<String> from being generated in a CXF Web Service client?

You have to create a binding file as below, this will get applied globally and use it as wsdl2java - b "bindings.txt" "wsdl"

<jaxb:bindings version="2.1" 
xmlns:jaxb="http://java.sun.com/xml/ns/jaxb" 
xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc" 
xmlns:xs="http://www.w3.org/2001/XMLSchema"> 
   <jaxb:globalBindings generateElementProperty="false"/> 
</jaxb:bindings>