The Unified Rules of MMA are ironclad and were made to transform the events that promotions like the UFC put on from pure martial-arts fights into a combat sport. The rules can be found on the ABCBoxing.com website and are explicitly stated.
Most of these rules make sense and actually help fighters from getting injured or seriously hurt. While it removes martial-arts techniques that use attacks to soft areas like the throat and groin, it makes the sport watchable for the masses.
It also makes it so those who haven't practiced martial arts all of their life can pick the sport up and learn. In the end, these rules help MMA grow and progress as a sport.
There are exceptions to the rules when it comes to how beneficial they are, and two exist as of now: not allowing downward elbow strikes and not allowing fighters to stomp on downed opponents.
The rule eliminating downward elbow strikes, which are also known as 12 to 6 strikes is a danger to the professional lives of fighters.
When a fighter is in the heat of the moment and landing strikes against a downed opponent there is a chance he might swing some elbows in a downward pattern. These elbows have very little chance to damage the opponent.
Elbows are most dangerous when coming from an arced angle because they can build momentum in a way that downward strikes can't. To limit one kind of elbow and not another is ridiculous and shows that some rules were created while the sport was in its infancy.
This rule is the reason that Jon Jones was disqualified in his match against Matt Hamill. He had dominated the fight and because of the slightly different angle he threw his elbows, he lost.
The other rule that needs to be done away with is the inability to stomp downed opponents.
In PRIDE, this rule allowed fighters to not have to either wait for their foe get up or to have to follow them to the ground. Instead, a middle ground was there for them to use. Unlike kicks to a downed opponent, stomps lack the angles and pressure needed to cause serious damage.
While stomps can still damage an opponent seriously if left unchecked, both the fighter's training and the referee should be able to stop such things from happening.
It would also make downed opponents actively try to either improve their position or stand up quickly, which would eliminate some of the stalling fans see in fights.
MMA is a sport and it needs rules, they just need to make sense. Most are, but these two need to quickly be removed if the sport wants to get better.