If your MacBook is properly configured, it should hibernate, so that you can easily resume your work, after you plugged in power supply. So I see no benefit from this app...
That's one of the key points: Sometimes properly configured MacBooks don't come out of hibernation properly. Also, I'm also trying to get rid of the annoyance of seeing your laptop hibernate when you could have done something about it. Maybe that isn't a pain for you, but it's a pain for me.