Exactly. Primality is nothing more than a misleading intuition pump to make you think in terms of "innocent bit of number theory", instead of "encoded data file

Exactly. Primality is nothing more than a misleading intuition pump to make you think in terms of "innocent bit of number theory", instead of "encoded data file". Even the term "illegal number" is designed to make you think this way; somehow, "legally protected secret" doesn't sound quite so absurd.