Some great points.
I'm not sure I would agree with all of your thoughts on sports, like MMA. For example, you say that the goal of sports is to prolong the combat, and you speak about a feeling out period. It sounds like you're confusing strategy with sport, and then drawing some pretty sketchy generalizations about the nature of sport. In every sport, I would agree that the rules shape the training. however, the goal of any sport is to win. And in MMA, the techniques used are designed to finish the fight as quickly and efficiently as possible. Each fight and each fighter will go into a match with a strategy in mind. Some will be more aggressive, while others will not.
Point, though, is that this isn't unique to sport. I would say that fights are the same way. Not every situation is the same. In fact, outside of a sport, there are an almost infinite number of variables to contend with. To sum it all up as "a serious fight, in which two opponents close very quickly and violently" is a gross oversimplification.
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I realize that I am oversimplifying and generalizing. But wouldn't you agree that these are sound points in most contexts? Consider the difference in context.
Combat may not, and usually will not be by consent. The fact that I even consent to combat in the first place changes the entire nature of it. In sport fighting, especially in striking sports, participants actively stay out of contact and keep their distance, carefully striking in and out of range. Unless your opponent consents to this kind of fight, there won't be a fight. If you want to hang out at a distance, I'm free to ignore you. I'll just turn around and run the other way. This is common sense, of course, so no-one who is assaulting you is ever going to engage in distance fighting. In sport fighting, I don't have to engage my opponent straight away. I don't have to stay on top of him. I can be more cautious; he isn't going to try to escape, call for help, or pick up a weapon. Moreover, the same levels of fear, aggression, and adrenaline won't be present.
In regards to prolonging fights, just look at boxing. The rules and equipment serve to artificially prolong the fight quite a lot. You're wearing big padded gloves, you have rounds and timers, and you're able to do things like clinch and hang on to your opponent while you catch your breath. Of course, some sports are better about this than others. However, the very nature and context of the sport often serve to prolong it. Usually, the fight is prolonged by virtue of the fact that both participants study the exact same arts in-depth. If you're rolling with someone in BJJ who is experienced, in contrast to someone who has never even done BJJ, won't the fight last a lot longer because he is able to fight you with your own style? Now, what if someone who has only done grappling confronts someone who has only done a striking art? That fight will end much more quickly; either the grappler will get in, and take down the striker, or the striker will knock out the grappler before he can get there. One way or the other, the fight will be over pretty quickly.
My only point is that there are more general issues that have a profound shape on the context of the fight. Let's consider another. You're an experience BJJ practitioner, so perhaps you already have an opinion on this. BJJ interests me as a sport, but I would be very careful about how I use it in an actual fight. Going to the ground in a sport context isn't too dangerous. It's just you and your opponent, in a controlled environment, and on a mat. But what about on the street? Concrete and pavement alone is reason not to do many techniques that we see in MMA and UFC, such as diving down and going after someone's legs or ankles. Moreover, going to the ground leaves you very vulnerable and unable to move or escape if you need to, which are very important considerations if there are other people present, or possible weapons involved.
So, that's kind of what I'm getting at. Sports do well to develop very specific sets of skill, but sometimes they are too specialized or limited in their focus. Just take target shooting as an example. Many target shooters will modify their rifles to make the barrels extremely heavy, and put scopes with insane magnification on them. Is this practical for combat and self defense? Far from. But because the sport is only concerned with hitting the target, it works. Another example would be Nascar. These cars are very specially designed. They're extremely low to the ground, and are only designed to turn in one direction, with very limited rate of turn in the other. These vehicles are the absolute best at what they do, which is going around a flat, circular track. But they would be quite useless in any other context.
MMA is probably better in these regards than most sports, but there are still very important factors to consider that limit its scope.
My comment about "arts trained by people who compete in combat sports being effective because they're simple" was mainly in reference to MMA. While I realize that this is a generalization, and that not all people who compete in MMA fall into this category, a whole lot of them are not so much interested in martial arts as they are in fighting. Just look at any number of MMA gyms. They usually teach integrated courses comprising techniques from BJJ, Boxing, Kickboxing/Muay Thai, and sometimes bits and peices from arts such as Karate, JKD, and Judo. So they're not studying these arts individually and in-depth, but rather just adding techniques and ideas to their fighting repitoire. And for this, the simple arts (or, simplified arts) are most effective, because someone who just wants to learn to fight doesn't have the time and effort to become proficient in a wide range of traditional martial arts. Better to learn a simple, easy to apply art such as boxing or muay thai than to pursue something more traditional that would take a lot more time and experience to learn to apply effectively. Of course, this is usually not the case with more specialized competitions; anyone competing in a Karate or BJJ tournament is going to be there for the art, most likely. But even in Karate, for example, many Karate schools are getting further and further away from the art, and are more just focused on sparring - treating the art more like kick-boxing than a traditional martial art.
One person who I really enjoy studying in my art is a man by the name of Wong Shun Leung. He came to Wing Chun already as an accomplished fighter, and a boxer. This was during the mid 50's when the tradition of "beimo" or "challenge fights" still existed in the culture of Chinese martial arts. And though he often fought in the ring in his early years when he practiced boxing, it was the no-equipment, no-rules challenge fights that he was really interested in. He came to Wing Chun after witnessing it in a challenge fight, and then visiting Yip Man's school and having a go with Yip Man and one of his students. From there, he went on to become one of Yip Man's top students, and probably more than anyone else, made it as well-known as it is today (at least in Asia) by means of his many challenge fights in Hong Kong. He was very intelligent, and very pragmatic, and I feel he had a better understanding both of combat in general, and of his own art, than most martial artists (both within and without Wing Chun). Most interestingly, because of his background as a fighter and a boxer, he often spoke of the differences between sport and combat. So, if you're at all interested in this topic, I would recommend researching him.
Here's a few clips dealing with him on youtube, if you're interested:
You can find many great, detailed interviews with him and his students. So, even if most of us haven't experienced combat ourselves, I feel that we can learn a lot and get an accurate impression of it from those who have.
