I don't think the 2nd-and-goal interception play was a bad call. Yes, the conventional wisdom would have been to go Beast Mode and run the ball in. However, with only 0:20 seconds left and one time out, you can do two runs. A first failed run would take the clock down to about 15 seconds, then Seattle would have been hard-pressed to run the second play and then get a fourth down off before time expired.
Pete Carroll's strategy of trying a pass on second down is better clock-management. If the pass goes incomplete, the clock stops with about 15 seconds left. They then could cue Beast Mode, try a run on third down, call time out, and have a do-or-die fourth down try available.
Only a jumped route on the pass kept that from being seen to be prudent. With 20-20 hindsight, it was a bad call, but it made sense, just as move Bill Belichick made in 2009 to go for it on 4th down in his own territory made sense. Both went again macho conventional wisdom; Carroll was supposed to smash the thing in and Belichick was supposed to punt and let his defense keep Payton Manning from beating them in a two-minute drill.
Both gambits flopped, but were only bad with 20-20 hindsight.