Concealing the meaning of transmissions is contrary to the purposes of the amateur radio service. There are perfectly serviceable radio bands, modes, and services for those wanting to transmit encoded messages, just like there are for those wanting to broadcast, transmit music, engage in commerce, etc.
I think the goal is mainly to avoid people doing things that aren't useful to the amateur radio community on the fixed amount of spectrum made available by physics. (Well, and some Cold-War-era paranoia about foreign spies, but...)
The idea is that the amateur bands are a commons of sorts for everyone to use and enjoy. As somebody else said you're perfectly welcome to transmit encoded messages on nets designed for that.
