This has to be the least important thread ever to be started on PPRuNe...
It is also the most puerile policy by Qantas/Jetstar/Tiger. Cathay Pacific don't do it nor does the RAAF VIP squadron.
I recall the original purpose of dimming of cabin lights at night for take off and landing in the old TAA and Ansett was so that passengers could enjoy the City lights. At least that was the hosties were told to say. The real reason was night vision adaption by passengers and cabin crew in case of passenger evacuation bright cabin into dark airfield even though that was a false premise. Despite the dimmed cabin lights passengers were permitted to have their overhead reading lights on which of course permitted them to read the emergency card in the back of the seats but which neatly destroyed any night vision adaption for passenger evacuation.
Notwithstanding the pilots had no night vision anyway due to the glare of runway lights and landing lights. Talk about inconsistency as far as the realities of night adaption was concerned.
Compare that with the serious business of night vision in WW2 where night fighter pilots wore dark glasses in dimly lit flight crew rooms so they would be night vision adapted in case of a scramble at night.
Then a certain South Pacific airline started a policy of turning the cabin lights to dim for all take off and landings because it was considered a good idea so the cabin crew would not forget to dim them at night even though that was a total waste of time since passengers wearing glasses could often not be able to read the safety card without the lights being bright and some could not focus where the exit doors or windows were at night unless cabin lights were bright.
Fast forward to now, apparently where cabin lights are dimmed or even turned off for daylight causing inconsistencies of light coming through passenger windows but the ceiling in shadow.
So what is the real reason why cabin lights are dimmed for departure and arrival? If it is for night adaption in case of evacuation, then cabin staff are not allowed to say because that might alarm the passengers. So the excuse is given it is to enjoy the city lights. But how about lights dimmed in daytime? There are no city lights to enjoy. The whole policy is sheer nonsense - a myth from war movies where night adaption was a pilot thing and you need at least 30 minutes of total darkness to get night
adapted.