The EndpointRegistry still exists, however it's no longer registered into the mbean server and thus not shown in the jmx-console. The only meaningful attributes it might expose is the deployed endpoint list, is this what you're looking for? If so, I'll create a jira issue for you.
Yes, that is what we used the MBean for. We have automated monitors that periodically check the state of the services by calling the MBean, iterating throught the endpoints and checking their state.
Having a standard interface for accessing the WebService registry would be useful.