For a linux kernel developer to complain about any other project's bug tracker is ironic indeed. The standard linux-kernel response to any bug report, no matter how obvious and serious, is as follows. "Could you please test 2.6.42-rc2-pre6-mm17+git20080909153242.8818?" And although the kernel has its own bugzilla, kernel developers seem to ignore it as a policy.
I happen to think Launchpad is very helpful both to developers and users. Users think it is a hassle to 1) find the upstream bug tracker, 2) register for an account there, 3) file the bug, and 4) drive the process through to the end. The fourth item is especially true when the upstream has a bug tracking system that they assiduously ignore. It's very frustrating to file bugs in GNOME's bugzilla or Freedesktop.org's bugzilla or the linux kernel bugzilla, only to see them rot for years on end. At least when you file them in Launchpad you get a good feel for how the distro managers are dealing with the upstream's defects.
Right now I have 53 bugs in Launchpad and only one of them applies to Ubuntu proper. The rest are all upstream bugs, and from my perspective as a user I'm completely satisfied with Launchpad's ability to drive the resolution upstream.