Okay, here's the deal. When the Enterprise (TNG, of course) is under attack, and Riker says 'Red Alert' in the way that only Riker can, the main overhead illumination goes out, and all we're left with is annoying red alert bulbs and indirect lighting from the floor.
Why?
Okay, I can see they wanted to make The Federation a lot like the Navy -- So when a Destroyer is in Enemy waters at night they kill most of the lights to avoid detection. But would that really work in space? How on earth will killing the lights on the bridge help conceal a craft that is on order of scale large than Westminter Abby? Are the Romulans really going to say "Well, gee, that *looks* like a Federation ship, but there's no lights on in the Bridge, so I'm sure it's just our imagination. Lt. FookJub, drop the shields and put the large, comical bullseye back on the underside of the ship."
I mean really.
The_Custodian: I know, I know, I thought of that... but none of it is nearly as funny if you put it like that. I need laughter to justify my existence!