The purpose of the GPL is not to prevent people from modifying and building on the code. The purpose... well, let me quote from http://www.gnu.org/licenses/quick-guide-gplv3.html :
There are four freedoms that every user should have:
the freedom to use the software for any purpose,
the freedom to change the software to suit your needs,
the freedom to share the software with your friends and neighbors, and
the freedom to share the changes you make.
The GPL is a clever legal "hack" to achieve this, by allowing the code to be used only by others who agree to play by these rules. If the law were changed to enforce these rules directly, then no GPL would be needed. And eliminating intellectual property law restrictions on the use of code would get almost all the way there. (Companies would still be free to "protect" their code through secrecy: releasing only the compiled version and not the source code, but decompilers are pretty darn effective.)WTF?!? No way! (although to be fair I'm not exactly sure what you mean by "use of code").
Companies would still be free to "protect" their code through secrecy: releasing only the compiled version and not the source code
This is exactly what the GPL is designed to avoid.
As you quoted above "the freedom to change the software to suit your needs" - that requires the source code!
...sort of. Source code access is important, sure, but here are a few more important issues that are basically orthogonal:
* The right to redistribute software
* The right to modify software (without source code?!?! Sure; imagine if I took Windows, removed the license protection code, and distributed that copy to you).
* The right to use software -- this, incredibly, can be a problem:
http://jalopnik.com/192843/robot-let-my-car-go-new-jersey-ga...
Only if distributing software without its source was also made illegal.
I'm not saying it is a realistic possibility in today's world, but it is not as though the copyright system is the only system we could have.
Nothig. But then, a company wouldn't have the entire governemnt's power to persue and extract money from people using their software. It's a completely different equilibrium, you can't just look at one side of it.
And I'm not saying it's a good thing either. Altough I defend that it's not smart to depend ("depend" excludes games, by the way) on proprietary software, I never tought it was immoral to create it, until the NSA scandal. Now I don't have any firm opinion about it.
There are many, myself included, who would be happy with this endgame. As long as no one can ever be prosecuted for creating a work, I am happy.
The GPL is needed because of the effects of copyright, not vice versa.
You can do this even with IP... if you're building SaaS instead of shrinkwrap, due to the GPL's most relevant restrictions here all hinging on the act of distribution of the actual software.
Without IP, there can neither be GPL (which licenses IP rights) nor close source proprietary (which is another model of licensing IP rights).