Greg Trippiedi from Hog Heaven wrote a terrific article on the "running up the score" debate that you simply can't escape if you're watching any NFL coverage today. You can read it here.
The only thing I will add to that is that I think a big contributing factor to what we're seeing thus far is last year's AFC Championship Game. The Pats were way ahead and dominating that game, and Peyton Manning led the Colts back in the second half to deny the Patriots another Superbowl. Belichick does not want that to happen again, so he's instilling a mindset in this team now not to let up, not to take the foot off the gas, or history could repeat itself. I believe that takes precedent over any "Spygate" motivation.