Plenty of reasons for the schools who actually play the game (and schedule it) to play it when they do. Sorry it doesn't fit anyone else's agenda.
The service academies think of football much more differently than any other school does. It's about teaching lessons to both the players, and also the other students, that they are expected to utilize throughout their careers as military officers.
It's not about advertising, alumni relationships, fund raising, media revenue, exposure, or any of the other things that you and I normally think of that are true for civilian universities.
It's about using football as a team sport to train military leaders, and that mission is not accomplished by a week zero game.