> > OK. But for me, Copyright violation deprives the *copyright owner* of the *value* of the thing you stole.
> It depends on what you call "value."
> Your software has the same or more of an impact on humanity if copyright law weren't restricting its copying.
> Your reputation in the world may be magnified if people copy your software willy-nilly.
If someone distribute something under the GPL license, all that the user can assumes is what is written in the license.
Maybe that copyright owner do not care about "reputation" or "impact on humanity"?
If he really did, he would probably have used another license, or a contract with strange requirements like usual commercial contracts.
What has to be "paid back" is clearly described in the GPL license, there is no point in discuting it too much - in simple terms just give back the source with your bug fixes and modifications - and the way to rebuild.
If you do not agree, either don't use it, or ask the copyright owner to use another license (maybe even for you only).
The government-provided copyright limited-time monopoly on a creation is for the society to evolve as a whole, it does not force the copyright owner to do anything more than enjoying the result of his own work.