Thinking about robots is thinking about cheaper, smaller and more energy efficient devices. For example think about smart phones and communications, think about information storage and transformation. Those aspects are not a single extrapolation of the past, they are a revolution. I see many advances in nanotechnology, machine learning and miniaturization that could give rise to a new revolution, this is like the transistor, we are at the verge of a big change.

The difference between MAD and STD is the use of the mean instead of the quadratic mean. Sometimes the quadratic mean is better, for example: if you have n some particles with velocity vi then the quadratic mean allows you to replace your system with another where each particle has the same velocity, the quadratic mean, this way the total kinetic energy is the same as in the original system, and this conservation of energy is a very important property in physics.