While communication is certainly a natural part of our existence, the various conventions of the English language are definitely human inventions and therefore superfluous to an examination of a person's intelligence. One of the biggest issues I had with my pubic school education was its emphasis on quantity over quality; I consistently scored lower than the people who could memorize more of the times table or who could recite the dates of every individual battle of the Revolutionary War or who could, per the opinion above, correct the grammar, spelling, or structure of every sentence I wrote - totally irregardless of the quality of the content of those sentences. The only positive I took from the experience was that greater adherence to the standards of English communication increase the chances that those who are listening will understand, but that was the only positive. So long as the point comes across commas, periods, and colons aren't terribly important.
The only reason I ever comment on people's grammar or spelling or structure is because I'm, personally, having a hard time understanding whatever is being written and I wish to have it clarified. While I respect eloquence, I don't believe that those who do not practice precise English are somehow less intelligent.
