In the same vein as compprob237's statements. Here is another one.. but first, of course the gov'ts involved won't back down on their encryption one iota.
Do they really think the bad guys will say "Oh, it's illegal to encrypt now... oh well... I'll just click send anyway." or "Oh, it's illegal to encrypt now. we better stop being bad guys."
Just like firearms, the bad guys won't care whether it's illegal to obtain, own, or use. They'll use it anyway. Meanwhile law abiding citizens/subjects/[insert your fav term for someone who has zero rights under their gov't] will suffer because of it.
Reality is the bad guys just make an excellent and handy excuse to strip the rest of us of rights that are supposed to be natural/inalienable or unalienable (at least in the eyes of the founding fathers of The United States.) Remember the Bill of Rights was put in place to restrict government from infringing on what was and are inalienable rights... or as they felt... God Given rights. (Yes. many were theists, not atheists or agnostics.)