Comment 3 for bug 592671

Well, I don't think the custom package installer should be responsible for knowing about, detecting and updating all such caches for all possible Linux distributions. That's why LSB and freedesktop try to unify (and simplify) all common tasks, desktop menu installation in this case. If your distro improves something it should do that "under the hood", keeping the proposed interfaces working, xdg-desktop-menu/desktop-file-install in this case.