Kojima did such a wonderful job with this game... It can't be said enough. The theme is indeed phantom pain from beginning to end, from waking up to wishing you were back asleep. I constantly feel like the game is missing something, and I don't think this is by accident. The entire time I had this overwhelming feeling of longing and loss hanging over me, never letting go.
I'm thankful so many people feel this way, and how much more perfect is it that there's actually a missing mission? The only difference between myself and many others is my belief that it's intentional. Kojima has created an experience unlike any other, a game intending to teach the player how painful sudden and irretrievable loss can be. Begging for more only plays into the hands of the game's main theme. MGSV will be revisited in the future as a spectacle and achievement in gaming... We haven't even scratched the surface yet! Not once has anyone brought up the heavy postcolonial themes running deep within the game, how loss of self and language- identity and culture, fuel into the theme of phantom pain... That desire to rediscover that missing element.
MGSV, like any great work of postmodern fiction, leaves itself open to interpretation. This doesn't render the experience meaningless, and neither does it signify laziness on part of the author. It's been a month since release, just enough time for my interpretation to settle in.
It's been a month and yet I still feel attached to the game, like a parasite, sucking every ounce of info out of it, hoping without reason for any relief at all. The phantom pain just won't go away.
_/¯ 
