I think it is because primes are widely accepted as remarkable. They are seen as things you discover - you don't invent them. The fact that they have practical

I think it is because primes are widely accepted as remarkable. They are seen as things you discover - you don't invent them. The fact that they have practical application is important too. Do we really want a legal system where you have to get clearances from the MPAA to make ship building software, for instance?