This post was so well written, I almost hate to comment on it...but I disagree with almost every point you make.
"Bend but don't break" is absolutely a strategy and not just a post-event observation. The Pats defense keeps everything in front of them and prevents the big play. The theory being that while you may get some yards, you won't be able to consistently get into the end zone enough to out-score the offense.
At this point, the theory you describe here has become essentially universal in the NFL. "Keep everything in front of you" and "prevent the big play" have become homilies for repeating to the media. As the NFL has become more and more of a passing league, with teams using more receivers more often and spreading the field
horizontally, this is what defenses have had to do to adjust.
Pittsburgh and Indy (to name a few) are not anything like that description. They use the defense as a weapon to create turnovers and change field position. If they don't keep the opposing team in tough down/distance or can't create consistent pressure, they are actually fairly easy to score upon.
No offense, but you really couldn't be more wrong in saying this about Indianapolis. The Colts (and Bucs) play the most pure Tampa-2 defenses in the league. This means 2 safeties deep, a speedy MLB playing halfway into the secondary, corners playing zone up front, LBs back off the line, and trying to get pressure with the front four only. If any defensive scheme can be called "bend but don't break," than this is it -- you can run at it or throw under it for a few yards at a time, but you can't get behind the deep safeties, and the smaller faster LBs will swarm to the ball carrier and prevent long runs. This defense was actually the first one designed to prevent what we now (mistakenly) call the west-coast offense.
As for the Steelers, again, they, too, have long been known for keeping two safeties deep, this time as part of their zone-blitz schemes. This was changed up of late to take advantage of Troy Polamalu's skill playing up closer to the line, but considering that another Dungy Tampa-2 desciple is now in charge there, it's unlikely that they'll become too much of a gambling defense, either.
As for the Super Bowl opening drive, of course the Pats wanted to get off the field. "Bend-but-don't-break" doesn't mean you don't try to make plays. It meant that they were willing to give Eli under routes that could result in 1st downs, with the expectation that Eli wasn't good enough to convert them all and get into the end zone (they were right). The downside was 1/6th of the game vaporized before Brady took a snap.
I'm sorry, but you're just addressing the actual reality of that first drive. The Pats' defense' focus was (as usual at the beginning of games) to clamp down on the run and force longer 3rd downs so they could send pressure. This actually worked out well, all except the parts where Manning identified the blitzes on 3rd downs, found the guys in the holes left open by extra rushers, and was able to make the throws with guys in his face.
During the entire drive, do you know how many passes Manning completed on 1st and 2nd downs? One. That's not something that happens on teams that are giving up the under routes. The Giants did their damage on 3rd downs, converting 3 third downs in obvious passing situations, all under pressure. This isn't a problem in scheme: any strategy that gets you five chances to end a drive is working: this was simply a problem of poor execution and tackling on 3rd downs.
The other downside is that Eli (generally excitable and not a great decision-maker) was now comfortable and confident he could keep the Giants in the game. Same with Feeley. Same with Boller. A passive defense is fine if that results in a positive outcome for the team as a whole. Not so much if turns average-to-garbage QBs into Joe Montana...and turns games with overmatched teams into close 4th quarter contests.
The fact that Eli didn't get as rattled as we'd hoped can't be blamed on the defense. They repeatedly got pressure. They clamped down on the rushing game and forced 3rd downs. Heck, for the most part, they got off the field pretty quickly: after converting 4 third downs on the opening drive, the Giants would convert 4 more the entire rest of the game. After an opening drive of almost 10 minutes, they didn't have another drive of five minutes for the rest of the game.