in letters, emails, forums and chats i dont really care about correct writing, neither english or in my norwegian
in litterature however, its much more important, because its a matter of a wholeness of a work. in the same way you cannot pretend to go for great realism in a painting, for then to ommit all shadows, you cannot pretend to write litterature, and then not write correctly
direct communication however is about making oneself understood. an additional little issue is that were talking about english here, and... lets be honest... apart from scandinavians and the dutch, everybody sucks at it...