Or charged by the US government. It is currently illegal to provide tools to circumvent copy protection on DVDs etc. Yes some smaller groups have gotten away with it, because either they are not the US or their location hasn't been found. But Apple is a big, very known company.
If Apple truly didn't want folks to do anything but buy from their store they could program iTunes not to take any outside media. Sure it would risk antitrust etc but if they really really wanted to they could attempt it. Frankly I don't think they care that much how you get it, but they aren't going to help you break laws.
