It's an interesting issue on many levels.
Not true. That's all I'll say.
No doubt about this. These guys are in amazing shape. Strength, endurance, agility, flexibility--they have it all. I remember seeing footage of Jens Pulver and Urijah Faber training before one of their matches. Few professional athletes can do what these guys do. From a purely athletic and conditioning standpoint, I have to admire it.
From a martial arts combative standpoint, MMA and UCF laid waste to many long-held myths regarding different styles of fighting and finally lifted the veil behind which many of these "schools" had hidden for decades. When put to the test, many highly-touted approaches were quickly revealed to be ineffective in a real-world setting. I think this was very important considering how many people around the world would spend years of their lives and often larges sums of money in the belief that they were learning to defend themselves when in reality, they were merely pantomiming lost skills from a bygone era.
I fully realize that not everyone who studies martial arts does so for the combative aspects of it. But for those that do, it is extremely dangerous and flat-out irresponsible to be teaching techniques that won't work when it really counts. I studied a lot of Chinese and Filipino martial arts when I was younger and the skills, conditioning and flexibility I learned have benefited me throughout my life. But the evolution of Mixed Martial Arts has helped to redefine how everyone from law enforcement, to military personnel, to the average person approaches self-defense. This is important to those who feel the need, or are required, to develop these skills.
All that being said, should it be banned? Well, in some states in the U.S. it already is. I don't follow it enough to keep track but my understanding is that some states have reversed the ban so I don't know what the situation is presently. In my parts, most of the New England states had banned it at one point but they could still hold matches at the Connecticut casinos because those are under the jurisdiction of the Indian tribal lands where the casinos are located. They have Sovereign status and therefore aren't bound by all the same laws as the state.
Various politicians and state's attorney generals were appalled by the violent nature of the activity and sought to ban it where they could.
I don't really agree with some of the sentiments here that banning an activity is somehow beyond the reach of what our governing bodies should be allowed to do. Let's face it, live gladiator fights to the death, with lions and tigers thrown in, would
definitely find an audience--but we do not allow it. There are limits to our "civilized" society. Many people find bullfighting abhorrent, and it is being banned in many areas now (I certainly understand the significant difference here that the bull doesn't have much of deciding vote in the matter to begin with).
Personally, I find the violent nature of UFC, MMA to be more than what I care for, but they are amazing athletes. I find the fighting the goes on in hockey equally distasteful but the blood lust of the fans is obvious in the cheers that any fight generates. At least with MMA we know what we’re in for.
As we (hopefully) evolve as compassionate beings, is violent, hand-to-hand combat something that we need for entertainment? I would like to think that it isn’t. And I would extend that to all sports that involve outright violence. I’m not unhappy that it’s banned in my state but I fully appreciate and respect the athletic prowess behind it. As I said previously, as someone with a martial arts background, I am thankful for the enlightenment that has come from the movement. I’ve never witnessed a professional fight in person and I can only imagine that the barbaric nature of the entire atmosphere would be amplified ten-fold to watching it on television. But if the participants are willing—and they most certainly are—then there will always be an audience for it.
[Edit]
I voted "no" to banning it worldwide primarily because I feel that is a very slippery slope to go down and that it would set a bad precedent for even our "own sport" of cycling. I could easily imagine plenty of people voting to ban cycling and keep us all of the roads if given the chance.