I separate copyright from the rights of an owner over an individual copy.
Think of it like a physical book. If I buy a physical book, I have the right to rip pages out of it, or rebind it with a new cover, or even scan it as a personal backup.
I also have the right to resale, so if I buy a book I can sell it to someone else, even if I've modified it (although I would need to destroy all of my own backups).
What I can't do is scan the book and start selling copies of it. That's covered by copyright.
In the same way, allowing someone to reverse-engineer and modify Photoshop, or even to share instructions on how to modify Photoshop, does not mean that they can turn around and start hosting copies of Photoshop downloads on their own servers and distributing them for free or for money.
Existing laws in the US cover this fairly well -- the problems I have are with EULAs that try to ban owner rights to modify their own software, and with the DMCA which makes it illegal to break DRM or tell people how to break it even if you're breaking it for a completely legal reason.
I don't want to get rid of copyright, but if you sell me an Kindle Ebook, and I break the DRM on that book to get it to load on my own Kobo reader, that should be legal. I don't believe an author has the moral authority to block something like that. It's not an obligation to distribute the source, or to allow anyone to do literally anything they want -- just to say that if content/code is executing on my device, I should be able to look at it and manipulate it. Once it leaves my device and re-enters the public sphere, feel free to start enforcing terms.