Re: Every single computer interface would be copyrighted
Oracle's point of view is that everything to do with the API is copyrightable, including the function names and the parameters they take. Whether you copy their header files and reimplement or look at the page and write a header too, they consider you equally culpable for infringement. If they win, that means the following:
"clean-room reimplementation": Have you seen the originals? And yours is similar (let alone compatible)? You infringe. Pay up.
"choose one of the many that are freely licenced": Did they copy? Did they see ours before they made theirs? They infringe. They need to pay up, and you need to stop using it or you will infringe shortly.
. "write your own": Is it similar? Do you use the same names and function contracts? Any of them? You infringe. Etc.
If that happens, I'm afraid it doesn't work quite as you specify. You've suggested that "The APIs that are locked up get ignored." That's possible, but what will happen is what happened with Java. It will get released under something that makes it look open until people use it. Then, the hidden loophole allowing changing the terms gets activated.
The only way to avoid it is to only ever use something that is and always was under a very clearly open license. We can do this now, and that's a great thing. But the only reason we can do that is because interfaces weren't copyrighted earlier. We have open implementations of C because AT&T didn't get to charge us. We have most of our OS and more complex language APIs because we had C. It didn't have to be C, but it did have to be something we could use freely. Without that, we wouldn't have very much, as each group trying to innovate would have to stay stubbornly in their own company or research group and not look at or use anyone else's stuff.