I may be the last person on Earth who uses kdesu to open graphical packages in root mode on the plasma desktop, but it appears I am now also dropping it, as it no longer works. One of the updates in the past week apparently disabled it. There is still an executable under /usr/bin, but if you launch it as a user, after you enter the root password it will fail with the message "org.kde.kdesu: Daemon not safe (not sgid), not using it." and leave a hung process that you'll have to kill manually.