If I modify my honda civic with a body kit I'm breaking IP?
If I put a sticker over the apple logo on my MBP I'm infringing on their design?
to me the modification of bits in MY Nintendo from MY Cartridge should be none of their business.
The things you describe are legitimately derivative works in the scope of copyright's worldview.
The issue is that viewing every single idea or concept as "property" with an owner and a price tag attached is a fundamentally broken model.
My original point about the idea that someone can own a song or a number as if it were property is fundamentally insane.
The fact that it being a violation or not depending upon whether the song is sung in public or in private illustrates that point nicely.