If you are emotionally hurt by the experience, though, you're welcome to stop by http://www.burnedforfandom.org and have a chat with a few sympathetic folks. That is why we are there, actually. Many of us had our first experiences with lawyers via our fandom, and because we did not know that 'This is how the game is played', we were devastated. So, we help each other through it.
But, now onto the meat of my letter. As part of Burned for Fandom, I have had to do a lot of research into the exact nature of copyright and trademark. It is my understanding that you can not lose copyright over a work from not defending it. You can, as I understand it, however, lose Trademark, as you have stated here. It can fall into the public domain due to lack of defense.
Your quote: “Even more important legally speaking: a creator of an original work, whether that be a big company or an author, who does not actively seek to protect his copyrighted and often even trademarked names, warning off any violators of their copyright, stands the chance of losing the trademark and/or copyright.”
Quotes are from: http://www.loc.gov/copyright/circs/circ1.html#wci The United States Library of Congress website on copyrights.
“Any or all of the copyright owner’s exclusive rights or any subdivision of those rights may be transferred, but the transfer of exclusive rights is not valid unless that transfer is in writing and signed by the owner of the rights conveyed or such owner’s duly authorized agent.”
Non exclusive rights can be transferred without a contract, but they have to be transferred...the copyright does not just disappear.
Copyright is amazingly difficult to get rid of, actually. I have been trying to place my own novel in the public domain, and there is no way to officially do this. I have been told that because of that, I am still considered the copyright holder of the work! It’s maddening.
Copyright does not cover words, short phrases, names, and things of that nature. Trademark does, though.
“Titles, names, short phrases, and slogans; familiar symbols or designs; mere variations of typographic ornamentation, lettering, or coloring; mere listings of ingredients or contents” (Library of Congress website on Copyright)