Try using Blender (3D modeling app) using this method. Blender on the go works just fine with a trackpad, but you're constantly using click-holding in that program. Do you really think constantly double-clicking-and-holding is faster than keeping your thumb on the button and holding when necessary?
This is an extreme example, but it illustrates the point. If you're missing fingers, then this is moot for you, but otherwise, being able to move with one finger, click with another, and "right-click" using yet another is the physically optimum way of using the elements at hand.
That being said, most people aren't at the point yet where the computer is an extension of themselves, like a musical instrument. When they get old and require becoming either cyborgs, or simply having their brains mapped to whatever flash drives evolve into, things will change.