My favorite use case is simple, I walk into a room the lights turn on, I leave the lights turn off. I open the pantry door, light on, close it light off. I also enjoy getting in bed and the house shutting down, lights, security, temperature all tied to my wife and I just getting into bed.
Where people go wrong is buying light bulbs, well now you have to keep the light switch on 24/7 or the wifi bulk isn't on to know it shoudl be off? like WTH? Just automate the switch and use normal lights. Wifi anything (wemo, etc...) sucks and almost always requires cloud service, why reply on the company that sells a $5 bulb to stay in business? insane.