i would say that it is a good thing, to maintain the copyright, but the extra tiles shall stays as an free willing oppurtinity.
I don't see how the copyright can be maintained by BGG, when the rights are with HiG. What does BGG's action has anything to do with HiG's copyrights?
Also, if HiG is strict about protecting its copyrights, they would probably have asked Gantry legally to remove all the custom tiles from this site, for instance, not to mention the numerous other sites out there.
However, I agree it is a good thing, because these fan-made sets are definately not "canon", and listing them would probably confuse players looking for infomation about the many (official) expansions and spin-offs for the game.
Edit: I reported the publisher of the 3 games as not being HiG and that the games were fan-made and unpublished. I presume that contributed to those 3 listings being removed. You can just click on the Submit Correction link for the game and it'll take you to a form.
Edit2: Perhaps the moderators can move this thread to the "general" forum as it is not really news...