I won't say they are useless, but the best way to get better at doing something is to do it. Much of the movements in the forms I've seen are not applicable to fighting, or aren't realistic techniques you would use in a fight.
I understand why you feel this way and I can just say that I can tell you are not a black belt in a TMA and have little knowledge about them. I was once the same way. This is not meant in disrespect at all and I thank you for the opportunity to inform you about something that is commonly misunderstood.
Let's take a move practiced in the first form of TKD. Front stance, punch with one arm, and elbow back with other. You are practicing three things useful in a self defense situation at the same time which would actually be used separately. By punching you make your punch stronger, faster, learn how to correctly breath while doing it, create muscle memory (example-practicing holding the fist tightly closed helps avoid injury because it becomes automatic-less chance of breaking your hand), etc. Almost the same thing with the elbow backwards. The stance can be used for balance against take downs, learning how to sit down on your punch -creates power, and provides stability in the knee joint and muscles supporting the joint which reduces chance of injury from practicing kicks repeatedly etc.
At a higher level a punch with a lower version of the front stance is taught as a lunging punch to the stomach or groin. Chuck Lidell and others have used this technique in fights in MMA matches. I personally love this technique as a great body shot most people don't expect in friendly matches. I really love this technique in a street situation because punching someone hard in the groin greatly increases the chances of defending yourself.Weight lifting is not what I was talking about. Weight lifting is just resistance training, really.
You brought up dancing. Thanks for making my point. Dancing can increase coordination, especially spectacle type dancing, yet it is even further removed from being applicable to a fight from even katas.
I agree that katas are more useful than dancing (Bruce Lee writes about dancing as a great supplement to MA training) and would agree with you about gymnastics. Jackie Chan practices TMA and lots of TMA teach falling and techniques seen in gymnastics. I learned how to jump over 7 bent over people roll and keep running. From practicing falling techniques in Hapkido I don't get hurt when I fall down even if I am flipped when I play basketball.
GSP practices gymnastics now and he is a professional fighter. TMA have always included this in the class. The specialists in this field are among the best in the world.
I wonder how many professional fighters and champions without a background in TMA have come to use forms as a primary tool in their training. I doubt many do, but if it was far and away more effective than normal training measures, that shouldn't be the case.
