Seattle was up by 13 with 2:40 to play.
Forget about 'running up the score' for a moment, and keep in mind that Green bay has a very good offense; what's the smartest play in that scenario?
1. A field goal from the 15 is almost guaranteed. Though it still remains a two-possession game if converted, the odds of a comeback drop quite a bit because they require not one, but two 2-point conversions. Even if that happens the score is only tied, as opposed to losing if the opponent scores 14 points. On the other hand, if you are seeking to avoid catastrophe, you don't risk a blocked field goal that gets run back for a touchdown.
2. It was 4th-and-1; run the ball for a first down to maintain possession, and then four more downs. Green Bay still had two more timeouts plus the two-minute warning, so you won't take that much time off the clock - but you will leave them with no timeouts for a potential comeback. The downside to this is if you don't make it, the Packers can score twice to win - whereas a field goal would have probably sealed the win.
3. Surprise the opponent by not running the ball, and instead going for a game-clinching touchdown. Downside is identical to running for a first down in the second scenario above.
I can see an argument being made for any of these three choices; I'm not sure if there is a right or wrong answer here.
Seattle has been accused of running up the score before (a three-week stretch in December of 2012 when they
beat Arizona 58-0; called for a
fake punt in the 4th quarter when they were up 47-17 against the Bills; and again when Pete Carroll faced old college rival Jim Harbaugh and beat the 49ers 42-13.
I wouldn't put this game in the category of 'running up the score', but I do agree with the OP - if the Patriots were in an identical situation and threw for a touchdown, then it would have been a big story nationally today.