There are artists who are anal about making sure their work is perfect, and then there are people like George Lucas who just can't leave well enough alone. If he had his way, I think all copies of the original Star Wars movies would vanish overnight. You would never see them again.
But here's the deal: copyright applies automatically to any works published. You don't have to register for copyright, you don't have to send your material to the Library of Congress. In fact, you don't even have to include a fancy little 'copyright' symbol, with date. You're not obligated to do any of this, it's just helpful in case of dispute. But the moment you publish, you have an exclusive right to decide how many copies are made -- the flipside is that your material is automatically on the track toward being in the public domain. You, as the artist, get rights automatically, and so do we, as the unwashed masses.
Because these works are automatically headed for public domain (which, without copyright, they would be in by default,) we have an interest in making sure at least one copy is preserved for that time. Basically, no matter what the author thinks on the matter, this material is ours, collectively, in the long run. The law retains this right for us, while providing the author with a temporary right over distribution.
How often, also, have we seen someone decide, after the fact, that they should charge subscription fees to access what was once free? When their copyright expires on those materials, you have every right to have your own copy, every right to do anything you please with it.
In order to secure the opportunity to do so, the opportunity to make use of your right, you must also have the right to archive copyrighted materials for later use -- for the day when they're no longer under copyright. What if something is published only to a couple people? Do they not have a duty to secure archives for the rest of us, to protect our collective future property? But can we, should we be obligated to, rely on each other to secure this? Should we be forced to rely on those who have paid their dues to get their own licensed copies of materials to archive those materials for us later? We have no guarantee that any other citizen will secure this for us, should we not secure it for ourselves?
So there you have it. The fair use right to archival copies of copyrighted materials -- making sure that, in 95 years or so, your grandchildren still have an opportunity to make use of their rights, despite artists, like George Lucas, who might want to erase all copies of what they see as mistakes. We love your mistakes, George. It's your new stuff we think is crap.