I'm not an advocate of the "incentive" argument. I'm sticking with private property/property ownership as the basis. As noted above, any artist/author can choose to protect or not and if protected to enforce or not.
One final point, these laws require the owner of the copyright to police it's use and take action if they feel there is a violation.
I understand and see validity in the arguments you put forth; I am also lumping copyright, trademark, and patent law under one umbrella because they are fundamentally the same thing.
As for the publishing house/tough cookies argument. As an aspiring author, I have already given away plenty of my work. In order to be a successful author, one must have a name. In order to have a name, one must submit more than a few manuscripts to all sorts of writing competitions. All of those writing competitions come with the disclaimer that the intellectual property I submit is no longer mine. It is what it is.
I do see e-books as a threat to the mass-marketed, serial novelist; I do not see it as a threat to great literature and the ability to make a decent living (note, not make millions like King, Grisham, Clancy, Rowling, Martin, etc.). I know that I, as a reader, have no interest in e-books. I despise reading on screens (even though I spend a good deal of time reading and typing in these forums). I still read old fashion newspapers, I print out journal articles I find interesting, and I buy books. I also despise crappy copies of books. There are a handful of publishers that I will purchase books from; outside of that, it had better be a great read that is only available through a certain source or I will most likely not buy it (font style, font size, margins, all matter a great deal to me).
I do not think I am the only reader who is this picky; I have met many others. I also do not find that my creativity nor creativity in general will be upset by the lack of copyright protections. I think that many authors who have made enough money that all they do is sit at home and write, with little to no anxiety and stress, produce texts that are much less creative and much more shallow than what they produced when they were struggling.
I do not think copyrights are going away; however, I would like to see the protections scaled back. Maybe give the author/musician/producer/artist five to ten years of complete ownership of their product then open it up to all the forces of the market.