Lots of fashion people are what psychologists call highly "visual-spatial" (think in pictures, not good at deadlines) and the rest of the world calls flaky. They think about the big picture, but ignore the leaky toilet until it crashes through the floor.
Your talented computer programmer, for instance, is a very creative person, but is highly sequential-analytical in his thinking. He could be very artistic as well, but would probably never go into fashion because it just isn't logical.
I agree with most of this. I'm a highly technical person who works in a support position in fashion (pattern maker). One thing that annoys me generally (a common perception of the public, not tFS per se) is the idea that technical people aren't creative. We are. Very much so. Believe me, it takes endless boundaries of creativity to make solutions of the problems designers throw at us. Creativity is not limited to drawing pretty pictures. Six year olds can draw cute pictures. It takes a great deal of creativity to find ways to make those ideas work.
It's TMI to explain why but I know quite a bit about the different types of thinking. Of them all, it is technical people who are more likely to think in pictures, the opposite of what most people think. It is described as "very male" thinking. Designers are actually abstract thinkers and better able to see the whole picture -that's why they're designers, they put the whole look together, the flow and feel of it (abstract-emotive). It's technical people who see parts of parts (not seeing the forest for the trees) which is good in that they build the minutia of constituent parts. As ever, this can be best described as an extreme. Consider autism. Autistic people are almost exclusively
thinking in pictures type people. Autistics are famous for being absorbed with parts of parts, the mechanical workings of objects. Again, extending the analogy to it's extreme, designers are more akin to those with
Williams Syndrome, the opposite of autism. Here's a quote:
Individuals with Williams syndrome are highly verbal and sociable (having what has been described as a "cocktail party" type personality), but lack common sense...
Outside of these extremes and having worked with thousands of designers, it is my experience that designers -successful ones- are highly intelligent. Relationships are important to them. The ones who seem to become most successful usually have at least a bachelor's degree if not an advanced degree. Perhaps surprisingly, few have fashion degrees. After 25+ years working in this business, the most successful ones aren't the ones who are most "creative" as far as generating ideas is concerned. They are successful in implementing an over all strategy, focus and direction. They're attentuated to their market, their buyers and their core customer. I'd say their first priority is VALUE, what their customers think that is, as opposed to throwing out the wildest idea they can come up with. They have bills to pay.
Then again, what is success? Is it landing in the pages of Vogue, that consumers who can never possibly afford you, know your name? Most of these designers declare bankruptcy or they don't even own their own name. Did you know that? Most of the successful designers I know own their own companies, live well, pay their employees a respectable wage and have a fanatical following among consumers who buy their brands. In fact, few of these designers even use their own name on their products.
move on. 
