Never in Oblivion did I ever believe it was too dark to see in a cave. The one time I even bought a Light spell was because it was hard to see all the items in the arcane university's lobby. Not because it was dark in there, but because I dump my junk on the floor in there and it was hard to find my enchanted rings in all the mess.
I'd really like it to be dark enough in some caves that neither you nor the enemy can see anything without obvious light sources. Not just the traditional fire-based light sources (candles/torches), but also such things as breaking the ceiling open to let in the sun or bio-luminescent mushrooms.
Seriously, I have a hard time believing any significant portion of the population can reach the age of 18 without experiencing "complete and utter" darkness.
Do I really have to ring the false information bell and flash my hypocrite warning lights? A LARGE majority of the population never experiences complete darkness. Complete darkness is 0% light emission. If you can see even a speck of anything then your are not in complete darkness.
Any interior room with no windows, lights go out (whether deliberately or accidentally)- complete and utter darkness. BAAHHAHAHAHAHAHAHA. No, seriously good joke. If you can see your hand in front of your face, then it is not complete darkness. If you can see a
Inside any room without massive picture windows on a cloudy night without lights- pretty complete and utter darkness. I don't feel like being a justified jerk twice in a row. Read about the http://en.wikipedia.org/wiki/Bortle_Dark-Sky_Scale. Note that the darkest is still not complete darkness with clouds or without.
Power outage anywhere on cloudy/non-moonlit night- complete and utter darkness compunded by the fact that it's everywhere. See above. Read it again.
Any time you're in a cave like the ones TES (and other fantasy RP) games are full of without a light source- complete and utter darkness. Real life: Most caves, no. Deep caverns, yes. Video-games: Very rarely. Not even pokemon has complete darkness in their caves.
Seriously, facts and opinions are different.
Facts come from reputable organizations who publish their results after proving scientifically. Opinions come from a single person saying what they want. My friend is severely color-blind and says the sky is green.