I'm not sure I completely agree - just because the code is visible, doesn't mean anyone has the rights to take it. Obviously you can obfuscate things, and add licenses - and in the end, someone can still come along and take your code and do with it as they please while ignoring any licenses you have put around the code - but you can't assume that all visible code is yours for the taking either.
You also state "Your code is your signature, and someone else's never can express your unique type of art. When it does happen (which it does), it is a matter of ethics, not law or government." - if licensed in a specific manner there are legal routes available as well. So whether you are the one writing the code, or you are the one taking the code this should be kept in mind.
Agreed. Case in point: I'm (successfully) selling a JavaScript Game Engine[1]. It's trivial to steal the code, yet I haven't had any problems with "pirates".
Of course it depends whether you're talking about a "cool blinking mouse cursor trail" or a framework that takes a bit of understanding from the people who want to use it. The former will be "pirated" far more often, just because the target demographic isn't as aware of licensing and copyright issues (or doesn't care).
You'd hate for this to come across as controversial, like there was a reasonable other side to the argument. How much of your code you reveal to end-users is simply orthogonal to whether it enjoys copyright protection. Code tends to be copyrighted by default.
You also state "Your code is your signature, and someone else's never can express your unique type of art. When it does happen (which it does), it is a matter of ethics, not law or government." - if licensed in a specific manner there are legal routes available as well. So whether you are the one writing the code, or you are the one taking the code this should be kept in mind.