In less stable parts of the world closed blinds are standard for night departures and arrivals because trigger happy locals find it easier to target brightly illuminated targets.
I have long suspected that dimming cabin lights for take-off and landing was originally inspired by similar concerns. It has been common practice for a long time, but the first time I recall it happening was on a Lufthansa flight into Munich some time around 1975. At this distance I cannot pin down the exact year, but it was diring the height of the Bader-Meinhof terrorism in Germany.