It is an unfortunate fact of life that content placed on the internet is subject to theft. That being said, sure, we've been looking at ways to restrict that sort of thing, WITHOUT going to the "registered users only" thing for access, like some sites have done.
If someone is determined to steal, they are going to steal. Even the lazy ones. With scripts freely available to take php generated content and convert it to pdf, html and other formats, it's a simple copy/paste of the story path to get the content ANYWAY, on any site, REGARDLESS of what's in place to attempt to protect it.
Something else to keep in mind, is that while these scripts are available, they're merely a stopgap for any site, and don't truly stop it. The best way to stop plagiarism is to quit rewarding the authors who do this. Until it becomes something where users are willing to step up and help put a stop to it, in the majority, this will always be an issue for any site.
One other thing to keep in mind, is that whatever IS implemented, I have to be careful that it doesn't affect the search indices abilities to index the site itself properly.