Let's analyze the three scenarios and see what is in the best interest of the NFL if they want to show meaningful games.
Option 1) Simultaneous: Both games meaningful for possible wildcard teams unless;
If SEA is winning in a blowout (unlikely), DET may give up with the wildcard still in play between SEA and GB.
If GB is winning in a blowout (unlikely), SEA may give up because the wildcard has already been determined.
THIS IS THE BEST OPTION - odds are likely both games will be meaningful to the end, and the teams will play hard.
Option 2) DET/GB before LAR/SEA:
Early game; Both teams are battling for the playoffs. GB in with a win, DET in with win and later SEA loss.
Late game; If DET wins early game, SEA in with win. If GB wins early game, meaningless game.
THIS IS THE NEXT BEST OPTION - The first game is guaranteed meaningful from start to finish. If GB wins, the late game does become meaningless, but only AFTER the wildcard is already determined.
Option 3) LAR/SEA before DET/GB:
Early game; Will be a meaningful game for SEA.
Late game; If LAR wins early game, winner gets the wildcard. IF SEA wins early game, GB in with win but MEANINGLESS GAME FOR DET.
THIS IS, BY FAR, THE WORST OPTION - It is the only option where a team may be playing a game in which they have no incentive to win (DET) while the result of the game determines the wildcard winner.
So why would the NFL not only choose the worst option from a competitive standpoint, but also arrange it so that the premiere Sunday game has a good chance of pitting a team with nothing to play for against a team with everything to play for?
I'll leave it to those with wisdom far greater than mine to put forth theories on this "inexplicably" stupid decision by the NFL.