My understanding of the issue is that the "Web profile" is a strict jee profile for web which includes only what is required for the specification. JMX is not a requirement for this profile and so it is not included. I'm not sure how you'd go about adding JMX to the profile as that gets into the guts of the app server and not the toolset.
Already committed to jbosstools trunk is a web poller, which checks host:8080 for a result to see when the server is up or down.