Phil Simms may be right; players may want to play 18 regular-season games (and to earn the money that goes along with that). But the NFL has yet to assume that’s the case.
In the pre-2011 Collective Bargaining Agreement, the NFL had the ability to add up to two regular-season games without any further negotiation with the NFL Players Association. The league surrendered that power as part of the latest CBA (so much for the notion that the NFLPA got nothing of value the last time around). But the NFL emerged from the last round of talks in 2011 the ability to reduce the preseason, whenever it wants.
The thinking, in the immediate aftermath of the signing of the current CBA, was that the league would at some point invoke the ability to play fewer than four preseason games, hoping that the union would respond to the reduced revenue by clamoring to replace the lost preseason games with more regular-season games. The fact that the league has yet to press the “shorter preseason” button suggests that the league isn’t so sure that the union would take the bait.
So that’s why the issue is expected to be part of the current negotiations on a new CBA. While some believe the league is merely posturing, intent on asking for 18 games and then giving up that point in order to look fair and reasonable, the better view is that the league has wanted 18 games for a long time, wants 18 games even more now (given the spread of legalized wagering), and will make a real push to get 18 games in the next labor deal.