The snippet of web.xml shown in Chapter 3.5 of the reference manual that is generated by the archetype:create command shows the use of the MessageDispatcherServlet class. Unfortunately, this by itself does not dispatch any messages.
I think that there might be some applicationContext-ws.xml and/or spring-ws-servlet.xml configuration that is also required in order for the MessageDispatcherServlet configuration to work. Since the use of the MessageDispatcherServlet is not used in the sample applications, the only existing example/explanation of this newer class is in the reference manual.
In my own case, after experimenting with the MessageDispatcherServlet config, I switched my application back to DispatcherServlet as it is used in the sample apps which then began working properly again.