Marty,
You raise an interesting point.
For most of the war, both the German and Japanese communications were quite well
known to their foes.
To answer your question, you need to think on the two basic levels...
Strategic vs. tactical.
It was utterly vital to the British that the breaking of the Enigma coder not be known.
Obviously it meant loss of life on a tactical level.
The complete information of german units, locations, status, who was on leave, etc., etc. was being broadcasted to the world on a daily basis. The strategic value of losing this data might be hard to comprehend when you are sitting in a foxhole, but think from Churchhill's position.
And the British didn't let their Allies know everything either.
I have also wondered why it took the allies so long.