While that may be true, the I think NFC has been more competitive recently. Over the last 15 years or so, the Seahawks have made their run, the Saints won it all, and the Panthers, Falcons, Cardinals, Bears, and Eagles have gotten there. Throw in the Giants, Packers, and 49ers, and that's more than half the conference.
Contrast that with the AFC, where it's pretty much just the Patriots, Steelers, Broncos, Colts and Ravens.