You create some scenarios for you lighting (respond to events, timed events...). And when you leave your system for a while, you don't remember what you used for what. Ever happen to you? :P
So maybe it's a nice idea to have a kind of 'where used' function for your lights and so?
This way, with one click, you could see where you're using that device.
And of course, it can help when you're need to debug something as well.
Sounds like a good idea for some web guy.