I think I heard their justification once was that they thought it was a bit of an anachronism that we'd press a hardware button to turn a PC on, but would have to go through a software route in order to turn it off. Every other electrical device usually has a single on/off button, and in a world of ACPI it's entirely reasonable for that to be the same as a default "turn off" action on a PC. Initiating a manual restart or true shutdown then becomes more of a power-user thing that, yes, perhaps it does make sense as a Settings panel.