I actually meant to say one division playing weaker DIVISIONS getting on over teams from a DIVISION playing stronger divisions.
If you go with best records, the risk of a highly competitive division (not necessarily better division, see NFC black & blue) knocking itself out is huge and also quite unfair when two teams from an uncompetitive division basically could always get in.
The division rivalry would suffer, winning division games would lose it's extreme importance and you would be looking at hockey style playoff seedings. Teams in the 3-10 seeding range would have nothing to play for at the end of the season, they cannot get the bye and are pretty much assured of getting in by December 1 or mid Dec. The only excitement would come from the say the teams trying to make the final two spots in the 11-16 seed logjam.
While 9-7 division winning teams (actually the 8-8 team may go deep this year) usually do indeed suck because they usually come from weak divisions, it is possible for the reverse to occur and that is the 9-7 team from a Strong division that knocks itself out by splitting the home and home games against each other. That is the problem I could see occurring. It almost happened in the NFC East this year, had Dallas not choked down the stretch and the Giants lost one more game.....it is possible that no teams from that strong division would have been in, given the seeding style.