Opening launchpad wasn't about creating competing public services. It was about making it possible for the technically proficient Ubuntu contributors to be able to stop _just_ filing bug and start filing patches to improve the tools they are required to use to do their work. It is possible to (and I'm sure people have) followed the instructions on running a toy development launchpad instance in order to poke at it without making the infrastructure investment of running it as a public service.
And since launchpad as a codebase was never designed to federate with a set of peer services (even though bzr clearly knows how), there's very little to gain by producing another public service that launchpad.net provides..and incurring the infrastructure cost. Everyone who loves what it provides will just use launchpad.net with no qualms about its open status. Now that its open, if it every closes again, someone may make a serious stab at forking the available codebase and creating an alternative implementation, but there's no evidence of that being a near term concern for anyone.