Packagekit is an amazing piece of software, however, the GNOME version looks much more organized and less cluttered. It would be positive for the users if you could make it look more like the GNOME GUI.
Well, KDE's PackageKit should not look like the GNOME one, it should look like KDE users are used to and according to what KDE HIG says (if any exists).
I think the KDE UI should stick to the KDE best practices, and UI guidelines, and not base the tools on the GNOME tools. I think you need to open a bug at kde.org for the component KPackageKit if you want to make suggestions.