UFC: Ethical?

I'm not a fan of professional wrestling or fighting, but recently I was in a conversation with some friends where the subject was brought up. I have nothing against people who genuinely enjoy watching shows such as these, but I do wonder about the ethicalness of shows like UFC, and why they become popular.

I'll start with popularity, as it is the easiest of the two to explain. Watching people fight is something that has appeared in nearly every stage of human development. Perhaps the roman gladiators is the most frequently acknowledged example of this, and as such, I shall start there.

Roman Gladiators were more than just slaves forced to fight, they were athletes; they trained, conditioned, and sometimes offered themselves willingly for the life of a gladiator. The ones who were successful were often rewarded very well, and those who were not, well, let's just say they went out of commission for some time. But why was watching the fights so popular? The simple answer is that people were bored, and would do anything for entertainment, but I think it goes farther. I believe that because war was so common at the time, fighting, and learning about fighting, was embedded into the life all the populace, whether they had fighting experience themselves or not. This would mean that in a society in which war is a frequency, recreational fighting will occur as well. So why is UFC so popular in the US, we are a peace loving democratic society? Right? Not quite. When you think about it, the country was created and formed upon a war, and there have been very few times in which the United States have not been in some sort of conflict. With the warring history of the United States in mind, it makes sense that that same passion or enthusiasm for fighting would appear in the  country's populace.