Thing is these things are on the internet yes, but legally afaik it's still not allowed to be spread around. Just because something is available online does not mean it is allowed to be spread by people. And where individuals will likely get away with it. If gaijin starts using it as a basis for game changes they can very likely get into legal trouble.

Just like sure, you can download a movie. And if you watch it somewhere in your own home? Odds are no one will care. Now, show that movie to a large group or start handing out that downloaded movie? That's when you start being in trouble.