MMA isn't missing anything. See, the proponents of Krag Maga, Karate, Wing Chun, whatever...they all claim to posses something called "t3h d34dly." An exaggerated belief in ones abilities, in that they believe the posses the secret ability to kill another person with their bare hands, in the form of eye gouges, neck chops, pressure points, you name it. The fact is they don't posses such abilities, because they have been tested time and time against Muay Thai fighters, Jujutsu Fighters, and MMA fighters. They were defeated horribly. And thus they use as an excuse NOT to compete in MMA, because they possess t3h d34dly. They don't compete because they don't want to kill anyone with their unique "powers."
So believe me friend, when I say, its been done before, search on youtube, wing chun against BJJ, whatever you want, you will see that what I have said here, is the truth.