It could be related to REST. A POST request is usually what is used for giving input to a REST service. It means that caches do the right thing with the request, if one happens to be in between the service and the client. But it might be nice to have a comment in /etc/default/x2gobroker-daemon warning that enabling debug will enable GET requests to make using a browser for testing possible. Also we need documentation specifying that only POST requests are normally honored, but documentation probably should wait until the product is closer to being finished :)