Ace Combat games (to me) don't have stories that set up gameplay, more that their gameplay requires dumbass stories to justify. It can be done well (see Project Wingman) but at the end of the day, with Ace Combat I'm here to fly funni plane. This obviously doesn't apply to all games, I just enjoy the goofiness of AC combined with extremely tight gameplay.
YMMV, if story matters to you it's not a great game and you should play project wingman instead