I agree with the you on the builder/construction pit and the air control examples. But don't underestimate what natural language can do for humans interfacing with computer systems.
The file system example:
"Computer, show me the document jake sent me the other day."
"Computer, I want to continue writing my thesis."
"Play the cute cat video again!!!"
Of course, it'll need agents with more deeper semantic understanding, advanced AI, NLP, computer vision, etc that is on the market today, but this is not a problem of natural language. See the work wit.ai is doing, we're pretty much there.
As I said, language is effective for general purpose communication, and the cases that'd work well for communicating with humans would also work well for also communicating with sufficiently smart computers.
But that's a different argument - the original discussion was about natural language replacing the current specialized systems (such as programming languages), and my point is that it's no more likely than natural language replacing musical notation or Photoshop interface.
You could have an interface where you say "computer, draw a funny moustache on that cat" in the same way that you can tell that to an artist; but if you want to define exactly what kind of funny moustache you have in mind, then both Photoshop and paper&pencil would be far superior interfaces than natural language.
The file system example:
"Computer, show me the document jake sent me the other day."
"Computer, I want to continue writing my thesis."
"Play the cute cat video again!!!"
Of course, it'll need agents with more deeper semantic understanding, advanced AI, NLP, computer vision, etc that is on the market today, but this is not a problem of natural language. See the work wit.ai is doing, we're pretty much there.