most people stop practicing the alphabet somewhere between 3 and 5 years old.
And they practice spelling words and making sentences with those letters thru middle school. In high school they construct compound sentences and use adjectives and adverbs, then in college, they get into prose, rhyme, composition, theme and once basics are learned, creative writing. A kata should not just be seen as an alphabet, but
a series of paragraphs (commonly 6-25) making up a chapter.
The kata I know best are short 2-man kata. They are sort of a "pure" version of a single technique, set up in a way that forces specific practice of certain principles.
These are the compound sentences or paragraphs that are linked together to form a full kata.
I suspect there's something about the organization and transmission of those arts that I just don't get.
Some of the themes a particular kata may concentrate on include: Evasion by body motion or stepping w/counter, physical conditioning, grabbing and throwing down, grabbing and breaking, defending against grabs, simultaneous defense/offense, and attacking with two weapons at once - concepts of application, and possible variations. This is all in addition to various blocks, kicks and strikes, footwork, and transitions between combos. The list goes on. These things can be practiced and transmitted to others via kata.
Nonphysical benefits exist as well, such as visualizing combat for an extended period of time.
The traditional katas were based on the fighting styles of the masters they were named after (like Chinto, Wansu or Kusanku) or to stress particular concepts and principles (like sanchin and naihanchi). They were not put together by randomly pulling techniques from here and there and sticking them together. Each one has been carefully crafted.
Your suspicion is valid, Gerry.