If you take without permission, you initiate force against that person, and the initiation of force is morally wrong. A system to prevent or allow for punishment of people who would take through force is appropriate.
I think you need to "reverse" your statement. If someone doesn't want anyone to copy their work then simply don't publish it.
What does "reverse your statement" mean?
The point of working in a field is to make a living, and publication is necessary to monetize your work if you make "artistic" products. Publication does not forfeit your property rights.
Either you own the fruit of your labor or you don't. Your copyright-less system does not recognize the product of your work as your property. That's not a just system.