While I am generally in favor of permissive licensing and accept the corresponding "yes, the code can get incorporated into other projects"...
That same copyright law protects my photographs. I am generally in favor of strong copyright laws.
There are also philosophies of software licensing that want to ensure that the user can have access to the code that uses my code. Under those philosophies, it is the protections granted by the limited right to prepare derivative works that allow that licensing to have teeth and enforce a copy left.
Without copyright, the GPL and corresponding licensing that is written with the desire to be able to guarantee the 2nd and 4th freedoms (access to the source for some product and ability to modify the code for that product) have no teeth and those cannot be guaranteed.
That same copyright law protects my photographs. I am generally in favor of strong copyright laws.
There are also philosophies of software licensing that want to ensure that the user can have access to the code that uses my code. Under those philosophies, it is the protections granted by the limited right to prepare derivative works that allow that licensing to have teeth and enforce a copy left.
Without copyright, the GPL and corresponding licensing that is written with the desire to be able to guarantee the 2nd and 4th freedoms (access to the source for some product and ability to modify the code for that product) have no teeth and those cannot be guaranteed.