From especially a small game producing company's perspective, I'd consider people ripping sets for use in another game free advertising. And from a large company's perspective, I'd consider it the complete opposite of noteworthy. No one is making money from this, and there's little to no monetary incentive for judicial action. All it would create is bad press for the company. And once again, there's the free advertisement appeal. For example, I would never have heard of (or bought) Hocus Pocus if not through jj2. Well, not entirely, but that's beside the point.

Being able to create levels with graphics from another game is a dream fulfilled for a lot of people in our community, too, I imagine. I for one used to make crude Sonic levels during elementary school on notebook paper, so the chance to actually design some (albeit not in a Sonic game) is appealing, even if just to realise silly childhood aspirations.

After rereading the original post, I think there is more to be said about some of the other situations described. When a person makes their own tileset and releases it on j2o, there is sort of an understood agreement between the author and anyone who uses the tileset that they can use it at their own discretion. Most well versed level creators know to credit the tileset maker at least somewhere in their own creation, whether on the j2o download page, the zip file, or inside the levels themselves. If a tileset author wishes for specific credit or usage requirements to be made or met, it's their responsibility to include instructions in the zip file, but honestly who is that anal about being credited? While it's reasonable to be protective of your own original intellectual property, at the end of the day this is just a silly game. Though just so you know I've been sending all of my level packs to the Library of Congress so don't (-) with me