Largely, it is the flexibility within that language. We don't have to determine in advance what might or might not be an eligible unauthorized use.
The flexibility of language has been proven to be useful as far as U.S. developments go, both in terms of building industries and in the potential to serve aspects like freedom of expression or having a free press. It is largely that element—that it removes you from having to figure out in advance what it is that you are trying to achieve.