You didn't understand me. It's not about being lazy or not getting enough exercise. It's about being more connected to your work. Maybe it's not the case for you, or even most people, but I am much more connected to what I'm doing if there is a physical component to it (writing down a lecture, even if I'm never going to read it, reading a book on paper that I'm touching, etc.)
The goal is to be a) more efficient and b) minimize the risk of developing RSI.
Nothing prevents you from still doing real exercise even if you have a keyboard made to minimize fingers movements: the two aren't incompatible.