Well, I don't agree with what seems to be the common definition of 'hacker' here. For me, hacking is the art (or vice) of making things do what they are not supposed (or allowed) to do. Plainly that.
Someone that builds a kick-ass revolutionary web application using Node.js is _not_ a hacker. He made a web site using a web site making tool. No rule bending anywhere.
Someone that builds a refrigerator for rural areas that works without electricity (as mentioned in another comment) is _not_ a hacker. He is an inventor. A genius. An engineer. Whatever, but _not_ a hacker.
Someone that takes a rotary telephone and manages to make it open keypad doors remotely (or whatever) is a hacker. A phone is not _designed_ to do that.
So answering your question, yes, for me, whoever bends the rules of machinery (even social or bureaucratic machinery) could be called a hacker.
But most definitely, 99% of people mentioned in this site should _not_ be called hackers.
I would still call him hacker. 'Bending the rules' is the characteristic of hacker.
I would say even 'bending the apparent rules' should also qualify being a hacker. So any genius / inventor having made a disruptive innovation is a hacker. He produced / created something which bent the apparent rules.
I like the term "biohacker" that someone here introduced me to. It fits with what I do to deal with my genetic disorder without drugs.
I tried the term "social engineering" to mean the same thing for social stuff. Turns out that means "con artist," which was not what I meant. I still don't know how to talk about that. Madonna comes to mind as someone who knows something about social hacking. She carried a tape around for weeks before running into the right person to give it to. She says she basically "begged" for the role of Evita, sending a videotape and eight page letter.
This simple, rural guy from India created
non electricity refrigerator for rural areas that dont get electricity. People now can save their veggies and food longer even in extreme poverty and no energy access.
He is now working on making a house with Air conditioning without electricity. Super hacker.