When I first started training in karate, I studied at a very traditional dojo run by Doug Perry. We had two classes of kata per week, one weapons class and a kumite class. Basic 3K karate meaning kata, kihon and kumite. It's the basic template for most traditional dojo. Traditional dojo usually try and set themselves apart from "modern" karate, the type of freestyle martial arts, which is more about stunt choreography and showmanship than practical technique, by advertising as not being a sport. The focus is on personal development, or spiritual growth.
I accepted this to be the case, because my sensei said so. I didn't really have any reason to not trust this because I hadn't done the research. The more research I do however leads me to believe that classical karate was intentionally changed and made more superficial to fit into a sporting format for recreation. This I believe is what gave rise to what we usually refer to as traditional karate or post WWII karate.
For a martial skill to be useful or practical it needs to be simple, easily deploy-able and effective. This can be supplied fairly easily. Think of police or military training. It doesn't take twenty years to train a soldier or a policeman. It can take a few months at the very least.
Traditional karate fills none of these criteria. It's techniques can be simple, but because of the sheer number of named techniques knowing the correct circumstance to use any specific technique is almost impossible. It's why you see karateka windmilling and losing their technique when pressed. It's not that they don't know any techniques, it's because they know too many. It's not easily deploy-able because it takes years and years of training to even become competent. How long does it take to master traditional karate. Probably 50 years. If you start at 30 years old you'll be able to successfully defend yourself by age 80. The failure of these two criteria make it not very effective.
When looked at from a sporting perspective, traditional karate makes a lot of sense.
Kata is used as performance art. Only a very superficial understanding of the kata is necessary. It's possible to win kata tournaments and have no idea what any of the movements mean. The number of kata available to a person is firmly in the double digits. This allows for extended years of practice just learning the patterns of these kata. It also offers a handy way to separate people into subsequent rankings. Kata 1-5 are beginner kata, kata 6-10 are intermediate kata and kata 11-15 are advanced kata. This basically ensures that a person can't compete if they only know one kata, no matter how good or competent they may be at it.
Kihon then becomes the artificial links that supposedly bind all the kata together, but they more importantly serve as the watered down list of techniques allowed in competition. Notice all the dangerous techniques that are designed to end a violent confrontation immediately are not among the basics, even though putting down an opponent is the entire point of karate.
Kumite is obviously the most sport like of all the aspects, but it can be ignored in some traditional dojo as if not participating in one event makes them more practical even though they participate in the performance art.
We're left with a sport that can be enjoyed by young and old. This makes it rather wonderful for recreation. When you're young you play tag, when you get older you perform kata and when you get even older you enjoy karate in a more internal way, and there's a handy rank structure to keep everything tidy and organized (for the most part). There's nothing wrong with this.
This is perfect for sport, but terrible for practical application.