One Reason To Choose A Strong Copyleft License Over A Public Domain Dedication / Release
*Note: in my view, a license is not copyleft if it is not Free.
In today's copyright environment, a strong Copyright license is a beautiful thing. (I encourage you to consider putting one on your works.)
It is not a perfect thing however and there are some problems and issues that go along with it.
Doing your best to put your work in the "Public Domain" (See: The Corruption of Our 'Public Domain' · Thursday August 05, 2010 by Crosbie Fitch http://www.digitalproductions.co.uk/index.php?id=252 for thoughts on this) will overcome some of these problems but I think choosing a strong copyleft license instead is a better option. Why?
If a work is in the "Public Domain" (Not copyrighted, copyright has expired, or copyrights purposely given up / donated to 'the public' in some way) anyone can use if for any purpose. This includes making a derivative of it and obtaining a copyright on the derivative and making money on that derivative while declaring "All Rights Reserved". This includes those whom some refer to as "copyright maximalists" just to be clear.
If everyone who was opposed to copyright maximalism were to release their works under a strong copyleft license, we would build up a pool of works that would advantage those willing to play a #Free game over those who refused to do so.
Now, nothing would prevent a copyright maximalist from enjoying the benefits of a work under a strong copyleft or even profiting from it. However, if they choose to do so it might make it harder for them to claim that it is impossible to make a profit from a work with a Free license. It might make it harder for them to claim that we need even stronger protections and harsher punishments for people to be willing to create and to profit from their creations.
My gut tells me that we are unlikely to see copyright maximalists making derivatives of works with strong copyleft licenses in the near term. This is why I think such a pool would give advantages to those willing to play a #Free game in a way that a similar pool of public domain works will not give.
Such a pool could be a game changer. If you would like the game changed, consider adding your works to such a pool.
"Free Cultural Works" defined: http://freedomdefined.org/Definition
"Free Software" defined: http://www.gnu.org/philosophy/free-sw.html