Here's a question for you, then: As a matter of course, most corporations hang onto their intellectual property as strictly as possible. This puts most derivative work based upon their property into the status of infringement. However, often this is not prosecuted. Is the infringing work really unlawful, then? Is the legally stated IP notice superior to the decision not to prosecute, or does the decision not to prosecute supersede the legally stated IP notice (until and unless said decision is revoked)?
To my understanding, when a copyright holder becomes aware of an infringement they then have the responsibility to act accordingly (I can't speak even with the veneer of knowledge on IP in general). If the holder ignores the infringement, that does add legitimacy to that "infringement" (possibly to the point where it is no longer an infringement). In Rowling's case, for example, she was aware of the Lexicon website for years and had previously claimed to have used it herself. If she thought there was a copyright infringement, then was the time to bring the cease and desist order to bear. That she waited so long hurts her case significantly (I think it would have been much more straight forward if she had acted immediately).
Of course, one must also realize that just because a copyright holder has stated something doesn't mean that such a statement is itself lawful or legally binding. They are free to claim tighter control on IP than copyright actually provides them.
Restricting it ought to require a good reason, and while profit for the property holder qualifies as a good reason, there is still a large amount of legal space between the rights they reserve and the rights they actually use.
Quite right, but the problem there is the nature of copyrights. There is a difference, for example, in Rowling ignoring the Lexicon for so many years (essentially giving it legitimacy) and Rowling’s own copyrights to; say, anthology publishing rights. Rowling currently has the legal right to publish her books in a single anthology; this right is reserved. She isn't using it, but that does not mean that other people could go, take that unused right, and implement it (at least, not legally. I wouldn't be surprised if there are illegal ones out there).
Yet, copyright is such a slippery matter. For example, is Rowling's general plot to HP copyrighted? If someone, say, went out and wrote a book about the following plot:
A young kid growing up in an oppressive family situation suddenly learns that he is one of a special class of children with special abilities, who are to be educated in a remote training facility where student life is dominated by an intense game played by teams flying in midair, at which this kid turns out to be exceptionally talented and a natural leader. He trains other kids in unauthorized extra sessions, which enrages his enemies, who attack him with the intention of killing him; but he is protected by his loyal, brilliant friends and gains strength from the love of some of his family members. He is given special guidance by an older man of legendary accomplishments who previously kept the enemy at bay. He goes on to become the crucial figure in a struggle against an unseen enemy who threatens the whole world.
Would Rowling have a case against them? Probably not, as that is actually a
quote from Orson Scott Card describing his book,
Ender's Game.
Does Rowling have a trademark on the word "Muggle?" Meh, that is hard to say, since Nancy K. Stouffer, the author of a book entitled The Legend of Rah and the Muggles, used it first (though her behavior in the lawsuit undermined her position), but Rowling is the one who made the word about as common as Kleenex (which is trademarked as well).
Likewise, it is dubious as to if Rowling could own the trademark to even the name "Harry Potter." In the specific context of the character, sure, but websites with the name (as per the 2000 Warner Brother's attempt at tyranny)? That is dubious, made worse by the fact that while the website wouldn't be included under a standard trademark of the Harry Potter name, the website's existence was entirely linked to the character.
Then there is Tanya Grotter, which is prevented from being published in English due to "copyright violations," yet none (to my knowledge) greater than Rowling herself committed in writing her work (except perhaps that Dmitri Yemets was more aware of his sources of inspiration than Rowling claims to have been). Indeed, the similarities that the Dutch Court found between Tanya Grotter and Harry Potter are almost laughable, including the fact that Tanya Grotter thinks her parents were killed in an avalanche and Harry Potter thinks his were killed in a car accident (which John Bibee’s character, John, -- from a series I am quite confident that you'd loathe -- thought long before Potter was a gleam in Rowling’s eye). The Dutch courts also found it similar that Tanya and Harry both had “two special friends.” One wonders if the Dutch courts have actually read many books.
Copyrights, trademarks, and intellectual property are a very tangled topic.