You may have heard that planes dim the lights during take off/landing so your eyes get used to darkness in the event of an emergency. But that's only part of the story. (yourmileagemayvary.net) さらに...
Sure want to have that extra electrical power available in case of a go around? Well maybe if we get to an all-electric airliner. Actually a crew would want to reduce electrical load demand in an engine out or generator failure but then again then aircraft will auto-shed to reduce loads in most cases. As a side note: the A-320 that landed on the Hudson River in daylight did quite well until some idiot opened the rear door before looking out!