An idle thought .....
I can ALMOST see the sense ... apart from simplicity / economy ... in using the breaker and NOT having a switch to control lights, in some applications.
The first is that HID lights, in particular, do not tolerate a casual flip of the switch.
Them there is the issue of voltage. Or, more correctly, untrained maintenance personnel. When the lights are 277 volt, you don't want the guy trying to use a 50 cent household switch ... or changing ballasts 'hot.'
