That's more or less what you can get with a Leap Motion. Some issues with tracking quality, but for gestures it works. It's a lot harder to make good screen interactions in mid air than one might think, so I'm not convinced it's all that great for normal desktop use (Having virtual hands in VR is cool though!).
It has been a while since I've used one and got to that opinion, and apparently software quality has gotten better. so if you are interested in this kind of thing it's maybe something to look into.
Guaranteed Gorilla Arm. You'll rapidly tire of that UI paradigm.
It's about choice.
Currently I lean back, cross my arms and hold a wireless mouse when I read long articles.
I just reached up and brushed back my hair. If this gesture also sent my screen scrolling, I'd be very sad.
If I could have floating gestures in front of my desktop I'd be very happy. Scrolling a page by waving my hand while leaning back in my seat. I think someone made something like this with Kinect.