I think that might be too subtle. I'd go with "It's like mailing a check in a transparent envelope with the amount and pay-to fields erasable and written in with a dry erase marker."
Even more so--"It's like forcing everything sent by mail to be sent in a transparent envelope and then publishing in the news every route that mailmen take and the easiest points where to intercept them."
Laws dictating how to/not to encrypt things make news really quickly so it takes even takes out all the fun in security research.
