Belichick in typical fashion doesn't owe anyone outside the team the details, but I agree with you that "coach's decision" doesn't satisfy the questions the media and fans have.
I for one still have the following questions............
"Ok, Bill, I understand this was a coach's decision and you do what's best for the team, but what is it about benching Butler that puts the team in a better position to win? Is it a bad matchup for a particular receiver/scheme/what? When the game played out the way it did in which the defense was getting gashed left and right, was their any thought to throwing him in there? Was the defense really better off with Bedemosi out there instead of Butler?"
When you make a controversial decision and it works out you get hailed as a genious. When you make a controversial decision and it not only fails but is an extreme failure, not only do you look like bad but I think it's perfectly acceptable for fans and media to want an explanation beyond the 'coach's decision'. He should be accountable for the move.