Coaches have to take a number of very important things into consideration, and one may be absolutely as important as another.
He owes it to the team to not only be prepared to win, but to gameplan with at least some degree of public perception about the overall "quality" of the win in mind in games where they are an overwhelming favorite. So, getting that big lead is important for not only that game, but also for the public perception. Beating Ga. State 23-17 vs. 56-0, for example.
The other consideration, just as important is also to his team.... and that is to play the reserves when the game is in hand, even if that means not getting the shutout. Run the offense, run the defense as practiced and planned, but with the back-ups in at some 'common sense' point in the game. Those players deserve the chance to perform on the big stage, in front of family and friends and teammates. That, imo, is just as important to the team as getting the blow-out shutout win.
The goal is to do both. But the W is most important, then playing as many guys as practical, then the margin of victory or maintaining a shutout.
Just my opinion.