It’s become a cue that writers all too often use to make extra, extra, extra sure their readers get it, which suggests one of two things: the writer is either concerned that his or words lack sufficient impact, or he or she isn’t quite convinced that the audience is smart enough to get it.
While there is definitely a time and place for the exclamation mark, do take a moment to question why you’re using it when you next feel the inclination. As for using two or three consecutively, don’t do it – ever!