John Pavlus in Your Body Does Not Want to Be an Interface:

The assumption driving these kinds of design speculations is that if you embed the interface — the control surface for a technology — into our own bodily envelope, that interface will “disappear”: the technology will cease to be a separate “thing” and simply become part of that envelope.

The trouble is that unlike technology, your body isn’t something you “interface” with in the first place. You’re not a little homunculus “in” your body, “driving” it around, looking out Terminator-style “through” your eyes. Your body isn’t a tool for delivering your experience: it is your experience. Merging the body with a technological control surface doesn’t magically transform the act of manipulating that surface into bodily experience. I’m not a cyborg (yet) so I can’t be sure, but I suspect the effect is more the opposite: alienating you from the direct bodily experiences you already have by turning them into technological interfaces to be manipulated. 

It’s an excellent essay. I especially like the distinction between Ready-at-hand and Present-at-hand technologies, and how our bodies shouldn’t become marionettes to technology.