Code words and it being "always better" to tell the truth:
Look at Pprune: members of the group develop fantastic explanations based on partial information from ongoing investigations; these explanations often far exceed what actually happened, and exceed in the direction of the posters' firmly held beliefs about The Problems In Aviation.
So I must question whether partially informing passengers will calm them down. If they think they're going die, their bias will be to interpret every bit of information or non-information as "OMG we're all gonna die!"
Code words work well in all fields, and I'm sure someone has started screaming upon hearing "cross-check and report"
There's something inherently frightening about being crammed into an aluminum tube and shot through the air with no control (or forward vision). And if something interesting occurs, there's very little chance of briefing the passengers with details as they transpire. Yet the British tabloids will always find passengers who were upset they were kept in the dark, fearful of their lives, instead of being given the 'Captain's-Eye View' (which, of course, not even the captain had).
In fact, cultural factors also come into play. I've seen Mediterranean passengers greet a fiery compressor stall on go-around with derisive applause. I've also seen a British student complain that the train known as the 'Glacier Express' was "too cold and too slow."