Cruentus
Grandmaster
In the UFC you have to remember that most of the people in the weight classes usually have the same reach. Even though palm strikes are strong, punches have more reach. So, now it is a question of circumstance...what does the situation call for? A punch, palm or elbow?
Another thing to remember is that in the UFC they train gloved striking (boxing, kickboxing) and the defenses that go with those sports. Historical significance is a big thing with those disciplines of fighting. Even though transitionwise palms would be good from striking to grappling, the MMA fighters train in styles where they hit with thr padded surface of a glove that is in the shape of a fist. Check out pancrase though...lots of palm striking there!
This is an excellent post.. I would like to add to it.
Intricacies like reach and angling become important issues for trained fighters in a ring/mat, where they need to use every skill advantage they can to face one opponent mano y mano under the rules of that engagement.
These intricacies become far less important on the street where there is no predictable environment or rules of engagement to count on. It is the person with superior tactics who inflicts the most damage the fastest who wins, not the person with superior fighting skill.
In the fight, there are environmental considerations and weapon considerations, and even unarmed the distance between fighters tends to close very quickly, with the outcome often determined within the first 5-10 seconds of the altercation, usually not lasting longer then 30-60 seconds. This is far different then doing 5 rounds at 5 minutes a piece.
Taking all these things into consideration, the advantages of closed fist punches are severely reduced. The only exception I make is for one who trains to punch bare-knuckle properly, and who can bring forth more significantly impacting strikes at a greater rapidity (with low chances of injury) with a closed fist rather then an open palm. But not only is this a highly individualized skill, even in that circumstance, the fight won't be decided by these factors.