People have the right to modify their consoles in whatever way they choose. Nintendo disabling consoles because they're modified sounds a little too over the top to me. Usually, the industry standard approach is to ban the console from any online functionality, rather than bricking it. And, honestly, people will always find a way to play pirated games.
Also, wasn't there a U.S. court case a while back that said that you can use whatever accessories you want, and not void the warranty?