1. I haven't heard of Nintendo sueing yet, but I know there have been cease-and-desist orders issued in Canada (and if they're here, chances are it's happened in the US too).

2. It's still their intellectual property, that's a very broad copyright definition. In some cases, it's easier to get out of, but when you're blatently pirating it, have fun in court, hehe.

3. More than enough games are constantly being rehashed. Being permissive with ROMs is totally screwing their future authority on their own property. Developers don't know what they might want to use next and thusly don't want to lose something that might make them $$$ in the future.

-Joe
P.S. This letter isn't condescending on roms, just the stupid idea of making a P2P program for sharing them. You can already download roms off Kazaa for anything from NES to Gameboy Advance to N64. It's a lot more legally protective for you and frankly, a hell of a lot easier