"The challenge of having "thinking machines" (as computers were once called) is that they make human thinkers—including the ones who invented them—stop thinking." - c'on. Normal machines (also called cars) does not prevent people from running in the morning. With "thinking machines" it's even less of a problem because of a pyramid of abstraction. One can always think one level up. Also thinking is much more than just data processing.

Though I agree that with invent of the cars population probably became more obese...