Nah, I like keeping it like is.
I like the preserved history of keeping the traditional divisions. Plus mostly speaking, they are geographically close, to cut back on travel.
If you aren't the best team in your division, you don't necessarily deserve to advance. The playoffs should consist of the best teams to come from each division; I'd rather do away with the concept of wildcards than to start ruling out division winners.
Ie, if the Cowboys don't finish ahead of the Eagles in the regular season, they don't get a shot to get to the Super Bowl. That is the privilege afforded a division winner. If you aren't good enough to do that, you aren't good enough to win the Super Bowl anyway, because someone else was better than you over the course of 16 games.
Yes, historically speaking, a couple of wild card teams have won the Super Bowl, but it's hardly more common than a division-winning team with a losing record.
I just don't see how it's some huge problem. If you are ultra concerned that a team who didn't win their division might be able to get on a hot streak and knock off all the other division winners and somehow that should trump the 16 weeks that they weren't the best team in their division, just make the playoffs a 32 team tournament with the last team standing the champ, then everyone gets a shot.
Otherwise there is no point in having divisions.