In the New York Times article The Smart Home Is Still Looking for a Market, Steve Lohr argues that smart homes haven't caught on because the benefits are difficult to measure against the complexity and expense. The article posits that energy management might finally provide the compelling reason for widespread adoption.
In my experience the main driver for home automation is security, followed by convenience and then, in third place, is energy saving. I never personally advocate for the latter because energy management requires a complex home automation system and to my back-of-the-envelope figuring, the capital and cognitive investment is too high to argue that it pays off.
That said, there are many simple technological solutions, that fall short of true home automation, but can help manage your home heating and cooling costs. For more on my approaches see Convection Wall Heater, Zippi-ty Cool Desk Fan, and A Smarter, But Not The Smartest, Thermostat.