It's sometimes very hard to change the license of an open source project. Technically you would need to contact all of the contributors to the project (and there may be a lot of them) and acquire their permission.
In any case, RIAA already has a license to use the existing software. That license can't be unilaterally withdrawn, unless RIAA violates terms of the license that invalidates it. New versions of the software can be released with the new license, but RIAA can continue to use the older version with the original license.
And, as other people have pointed out, this would create a software license that is "non-free", and therefore incompatible with other open-source licenses, causing all sorts of headaches with software distributions, and any other software that has a dependency on the software.
And if everybody add their own little restrictions on people / organizations they find evil, the whole thing could rapidly become unmanageable even if licenses are somewhat compatible when trying to combine codes from different projects.
This is not a good path to take, even if it sounds appealing.
Revenge is also often not the right response to a bad action, it can escalate where the opposite effect may be desirable.
Let's try other stuff and continue to allow RIAA to use our tools, they even may evolve for the better in the future and that would be great, no?
And it is not about revenge. It is about enforcing the spirit of those open source licenses. WordPress uses GPL to force users to contribute to open source.
Do you think the RIAA contributes? Instead they actively attack it.
Do you think the RIAA can evolve for the better? It has an explicit mandate to restrict copyrights. Its existence opposes the software they use.
True, sadly it is unfeasible. It is a nice fantasy.
This depends on whether the GPL includes (part of) the html-code distributed by the website (seems not, this is the domain of AGPL). GPL is widely known to be insidious.
If by rights, you explicitly mean "The right to be paid" then I think you're probably correct.
Although I'd note they're not really interested in having the musician get paid. Mainly just members of the RIAA.
Now - I have some sympathy for that view - I'd also like to get paid, and while I think the RIAA has little real value in the world, some of it's members certainly are working on the marketing and promotion front.
That said, I use many of these downloading services to save conference talks from youtube. So they're attacking a service I use legally for a useful purpose. At some point, ethically, I start to lose ANY sympathy for them as an organization.
In any case, RIAA already has a license to use the existing software. That license can't be unilaterally withdrawn, unless RIAA violates terms of the license that invalidates it. New versions of the software can be released with the new license, but RIAA can continue to use the older version with the original license.
And, as other people have pointed out, this would create a software license that is "non-free", and therefore incompatible with other open-source licenses, causing all sorts of headaches with software distributions, and any other software that has a dependency on the software.