I remember a quote from Bob Stoops from back in 2003 that addresses a side of this issue that is often ignored. This quote is more applicable to the high school level, IMO. But anyway, to paraphrase Stoops:
"These [starters] bust their ass every day of the week in practice, and it's not fair to them to pull them out at halftime of every game. We're not trying to humiliate our opponents, but at some point you've got to reward your [starters] for working their tail off in practice by letting them play."
In 2003, OU opened the season 12-0 and in those 12 games they really blasted a lot of their opponents (in particular, OU beat Texas A&M 77-0). But in those 12 games, OU had about 8 or 9 that Stoops had pulled starters early due to blowouts, and that time off was really adding up for the players. Jason White was OU's starting QB, and he had about 4.5 games worth of sitting the bench.
OU has been on both sides of ugly blowouts more than most teams have been lately, and Stoops has always maintained that while humiliation should be avoided if possible, it's not the winner's responsibility to ensure the score doesn't get out of hand. He said this even after OU lost to Kansas St. 35-7 in 2003. Yes, the same season in which OU beat Texas A&M 77-0.
Way back in the day, Bobby Bowden's West Virginia team beat Lou Holtz's William & Mary team by some unholy margin. After the game, they had an altercation:
Holtz: "I thought we were friends, Bobby!"
Bowden: "My job is to score, Lou. Your job is to stop me!"
Mike Leach (Texas Tech Head Coach who is infamous for running up the score): "Why is football the only sport where you're asked to stop playing? Isn't that the other team's job, to keep you from scoring? When did it become my job to keep my offense from scoring?"
Bottom Line, IMO, it's the loser's job to keep from getting blown out, period. A team should never have to apologize for winning by a large margin.