I know the reasons behind dimming the lights during take-off/landing and it's always interesting to hear other theories, but this thread is more about why lights are kept ON as opposed to why are they turned OFF
gcal, I echo your sentiments... You can pay 50-100 quid to go watch some guys kicking a ball about, or the same cash can buy you a return trip to somewhere nice (or to make money!) strapped to a pressurised, heated tube with two chock-off jet engines attached to it which will take you to your destination at 500-600 mph + in the stratosphere, and you even have a window to look at it all happening.
There's something captivating about watching the rural lights of some foreign countryside slipping slowly by. Buggers disappear when the lights are on
That's another point - I'd rather have the map and speed/altitude information shown on the screens the entire journey than some crappy movie that is on a screen about five metres away from me that I can hardly hear through the headsets, but I can't complain about that as it's probably what the masses want!