It never ceases to amaze me how prosaic, pedestrian, unimaginative people can persistently pontificate about classical grammatical structure as though it's fucking rocket science. These must be the same people who hate Picasso, because he couldn't keep the paint inside the lines and the colors never matched the numbers.
Good grammar is credibility, especially on the internet. In blog posts, on Facebook statuses, in e-mails, and on company websites, your words are all you have. They are a projection of you in your physical absence. And, for better or worse, people judge you if you can't tell the difference between their, there, and they're.