Copyright is a System of Oppression
Copyright is a system of oppression. You can't achieve liberation by using copyright, because you can't use systems of oppression to achieve liberation. Licenses like the MIT and the GPL work within the bounds of copyright. So what can you do that may be outside such system of oppression?
Disclaimer: We're not a lawyer. Please talk to your lawyer before attempting any of this.
For starters, you could make a notice of non-enforcement: a promise that you won't enforce the copyright. You can also require contributors to agree to the same terms, to not enforce it. However, neither of these would be licenses, and so it would be outside of the scope of copyright, thus subverting copyright.
This is a bit of a criticism of the Ethical Source movement, a spin-off of the Open Source movement with a focus on preventing and/or eliminating the use of community-developed software for oppressive purposes. It attempts to do that by taking advantage of a system of oppression, but the thing is, you can't achieve liberation by using a flawed system. You'll just leave ppl out. We can also use these same arguments to criticize the Free Software movement and even Creative Commons, altho those don't have the same strong focus on trying to liberate ppl from systems of oppression.
Nevertheless, this isn't to say the goals of Ethical Source are bad, or that there's nothing to be learned from it. It's just that it's not the answer to liberation. In the mean time, is it even possible to make a culture of unenforced copyright infringement? Most services have provisions against even talking about it...