English is a fluid language. So, of course, we want to teach kids to write, but what's the point of grading them on it? Absent a board of standard dictated by law as exists for some other languages, I don't see the point. With less emphasis in school on correctness, our language can be more fluid yet, with style guides keeping up with common usage rather than compelling common usage. It would be interesting to see whether the English language would improve as a form of communication if allowed to evolve unimpeded.
Note: Edited to remove my irrelevant comment about spaces after periods.