Sometimes Mac OS X has everything you need. But sometimes it doesn’t. Occasionally you need to do some kind of system work that your operating system just doesn’t support. In those cases, you need to turn to specialized tools like one of the three programs here.
Lights that go on and off, dim, and brighten, all by themselves. Appliances that respond to the time of day and the presence or lack of daylight. Coffeemakers that turn themselves on and off. You still can’t order an Earl Grey (as Star Trek’s Captain Picard does), but you can have your house obey your commands.