Quite simply Mexico is the next biggest market for NFL football in the whole world after the US.
Mexico has 20million viewers of NFL every Sunday and the popularity of NFL teams like the Cardinals, Cowboys, Chargers, etc is massive.
The NFL can make a ton of money out of Mexico, and tap a potential player pool to expand that fan appeal.
The NFL will always look for ways to make more money, and overseas markets is an untapped resource as far as that goes. THAT's why the NFL made such a big deal about it. Not forgetting it is the first regular season game EVER to be played outside the US. America's favourite sport goes to foreign shores - and that's a pretty big deal too.
Don't underestimate the popularity of NFL fooball in places like Japan, Mexico, Germany and the UK...