I think it's just a little disheartening to see so few people who care what their posts look like. Sure it's just a post and an occasional typo or incorrect choice of word is no big deal, but if I am going to put something out for the world to see, I would like to project my best image.
During an instant message conversation, where things are written and disappear shortly thereafter and you know who will see what you wrote the scenario is a little different, but many people of all ages and from all walks of life see these posts, and sadly, many of our students (and adults, too!) are not concerned about reflecting the intelligence and knowledge they do possess but rather utilizing the convenience of "casual rules".