I find that many Vulcan idiosyncrasies are a lot like those of people with high-function autistic-spectrum conditions -- a very rational and ordered thought process, difficulty understanding others' emotional responses, excessively literal interpretation of others' slang and idiomatic speech, a meticulous attention to detail and precision. I've always had some tendencies in that direction myself (though I've never actually been tested for the condition), and I prefer to be precise in my use of words and numbers, to dislike rounding things off or being too vague. (Although, for full disclosure, I must confess that Spock was my main childhood role model, so that could be a factor too.)
Perhaps the average Vulcan brain is more prone to that mode of thought than the average human brain. If anything, Vulcan education and philosophy actively encourage people to think along those lines. Maybe Surak had the equivalent of high-function autism or Asperger's Syndrome, and so the behaviors associated with that kind of condition are promoted by Vulcan culture. At minimum, it would be an affectation, but maybe their upbringing actually conditions their brains to work along those lines, due to the plasticity of the developing brain.
