I've heard many reasons.
First, tradition. The Cubs famously refused to play night games and did not install lights at Wrigley until I believe MLB forced them to do so when they finally made the playoffs in 1988.
The thinking was that baseball was meant to be played in "God's light" and that batters have always had to pick up the ball from the pitcher in the sun and not in artificial light.
With football, it's not as tradition bound, but you always hear how people love the Irish coming out of the tunnel with the sun sparkling on their gold helmets.
Second, NBC does have a big say. If I'm not mistaken I believe they paid for the installation of the lights at ND Stadium and may also pay for them whenever they are turned on. I'm not sure how much it costs to have them on for a whole game, but I don't think it would surprise a lot of people if a big part of it was NBC being cheap. Nevertheless, the lights are used for many 4th quarters during the season when the sun evnetually goes down, especially later in the season.
Lastly, wasn't there a big concern from the school about having students and fans tailgating all day? I seem to remember there being strong objections to night games because the school didn't want the atmosphere to turn into Death Valley in Baton Rouge.
I think in the end it's a combination of all three factors. Although there have been a few night games in the past during the Holtz era.
There should be one or two night games a year at home. Day games are nice and everything, but there's just something about watching a game under the lights. It gives it more of that "stage" feeling like you're watching high drama at a theater, you know?
