The modern NFL era makes it impossible to have a powerhouse that will make deep playoff runs and contend for SBs every year. The era of the Pack, Steelers, Cowboys, etc... winning multiple SBs in a short period of time is pretty much gone. The exception was NE however they have an easy division, and even their roster was drastically different from year to year. NEs greatest advantages were solid OL/DL and a QB who's wife made more than him so he could agree to very very team-friendly contracts to allow spending on FA year after year.
The modern NFL under Goodell has made sure that even the suckiest, worst, most pathetic teams in the NFL will make dumploads of money. So there is less and less incentive for greedy owners to take monetary risks to put together winning teams. Sure, there are a few owners who still try but not many who really put forth much effort or risk. We are in the era of football as a business, not football as sport-focused.
Which leads to the current system. An NFL team really has 3 choices right now, A) be a team like the Packers who has a great QB who will keep them relevant in the regular season and give them at least some chance in the playoffs. This is the team who has a figurehead of the franchise, like Arod, Brees, Brady (up till last year), Rothlisberger... and B) the team who strikes gold with a QB in the draft and happens to be able to assemble a team around them for a SB run before they have to pay that QB like SEA, KC, PHI... and C) be content with sucking balls because the NFL makes sure you are still rich despite how much your fans hate you (ahem CLE I'm looking at you).
