Here's an example. The Colts over the last decade. They've won more regular season games then anyone. But typically end up 1 game on out in the playoffs. In that entire time only 1 super bowl appearance and win. As a fan I'd be frustrated that my team keeps having great regular seasons, but doesn't do shit in the playoffs. If they are done after the first playoff game, who cares what their regular season was like.

Or the Jet's who only made the playoffs because the last 2 weeks they played teams who didn't need to play to win. So they were handed a playoff spot. Does them making the playoffs really mean as much as say a Dallas who played their asses off to get in?
If the Colts were my team, I'd be frustrated they haven't at least made another Super Bowl yes, but still pleased that they have had one of the best teams in the NFL the last decade. Losing in the post-season doesn't erase the regular season IMO, just like a Super Bowl loss doesn't erase winning 2-3 Playoff games and having a good regular season.

For the Jets/Cowboys comparison, the Cowboys had a better year and are a better team but the Playoffs can be a crap shoot. If the Jets somehow win this weekend and Cowboys lose, doesn't mean the Jets neccessarily had a better year....you can argue either side with good cause.