As SLF, I've always thought that the mechanism of letting the CC know they could get up after departure, by bonging the seat belt sign twice, somehow contributes to the whole thing.
Pax hear the bongs, see the seat belt sign flash, see the cabin attendants get up and start their work, and presume they can start wandering around too.
Any other way you can let them know without the "sheep" effect taking over?
I've also often wondered what the message acually was in Cantonese/Mandarin. Its always quite clear in English but its almost as if the thing is so mumbled and short in Canto that the locals don't even (want to) hear or comprehend it!?? Is the message the same???