The only use I could think of for this is data collection or whatever it's called - to see what people think of their programs. Why on Earth would someone want to have their emotions detected and databased? I'm assuming it's optional because you could disconnect camera etc but doesn't this kind of remove someone's free will to say what they want about a program? Or it could be added to someone's status - ‘John is feeling depressed today’ so people can see that and say stuff to make him feel worse? It's sick!