Why not? Why should something I create by nature be fair game
You've actually hit the nail on the head -- there is no natural right of copyright. In fact, copyright is in direct conflict with the natural right of free speech (which encompasses the verbatim repetition of what someone else has previously said). A copyright is nothing other than a privately-held but government-enforced right to censor other people. It shouldn't be granted lightly, and should be granted only when, and to the degree that, it produces some benefit for the public that outweighs the harm that it necessarily causes. (Ideally, only when the benefit is greatest and the harm is least)
Yes, I do. I would have to for everything I write - and that sucks big time.
Well, it would be your choice of course, but I find it unlikely you'd bother.
First of all, I'm not in the US, so it'd have to be some institution local to me. Now, copyright is international (this in great contrast to patents, btw). It would suddenly become local - I would register in Hong Kong (where I live and where my creations are made nowadays). Or should I have to register in every single country I want my work protected?
Copyrights are not, currently, international. There's just a lot of reciprocity. It's one of the things that needs to be dismantled in time. I'm really only interested in what the US does, but what we ought to do is to withdraw from the various copyright treaties and instead offer national treatment to the world, unilaterally. So if you want a US copyright, you wouldn't be discriminated against merely because of your nationality, residence, etc. (unlike the old days, when we didn't grant copyrights to foreigners) but you would have to do the same filings that our copyright applicants do. Between providing the forms in a wide variety of languages, accepting payments in foreign currencies, local support through our embassies and consulates, and the Internet, it shouldn't be too difficult.
Also if you would require someone to check "the registry" to see if a work is copyrighted or not, they'd have to check all registries in all countries, one by one.
No, only in the jurisdictions where they wanted to act. Just as most businesses don't bother getting patents in every country in the world (because they know that the amount of business they do in Burkina Faso, or Disputed Zone is too little to justify it), authors who don't bother getting a copyright in the US (or other places that adopt a similar policy) are allowing the work to enter the public domain there. So if you print books, you really only need to check your country's registry, and maybe only others if you ship abroad.
And while matching text is relatively easy, matching images is getting harder and matching video or music is even worse.
That's the notice formality. As with patents, copies should bear a visible notice somewhere indicating at least the year the term began and the rights holder's name. If an application or registration number has issued, that should be present too, if the rights holder wants to keep his rights.
Many of the stories mentioned above I published anonymously, and I like it that way. Yet anonymous doesn't mean no copyright
Why not? If you're truly anonymous, and not merely using a psudeonym, how would you have filed? Land can't be owned anonymously, nor licensed vehicles, nor patents, nor registered trademarks. That's just the nature of the beast. You'll have to decide whether your secrecy outweighs your desire for a copyright.
Photos that I post online, or stories that I post online, source code that I've published on github and sourceforge, even though I don't expect any economic benefit, I like to have copyright protection for
Oh, I'm sure. It's because there's no downside for you, so you can mooch off of the public. It's very wasteful. Just imagine if you were a farmer and we were talking about a field of grain. You grow thousands and thousands of acres of wheat, but you only use a little for your own consumption and let the rest rot in the field. And should other people want to take some, you say no, because it's yours!
If you're using your copyrights productively in an artistic business, that's great. But if not, if you just want to be a camper, why should the rest of us put up with it? How does it benefit us?
The current registration system in the US may work nicely for those that register their work
It's not bad, but could be a lot better. And remember, the US required registration of published works for which a copyright was sought for a very very long time, and this didn't begin to change until the late 70s. And it nevertheless worked out okay for the many authors, fine artists, composers, photographers, filmmakers, etc. that we had. It's not like our arts were stunted or anything.