The usefulness of emoticons is for the folks you don't really know well or/and don't know you well.
My real (read: we have known each others for years and years and spent much time together) friends will understand what I write and what I mean without the use of emoticons. They know my sense of humor.
The Internet allows an unparalleled method of communication, placing people who have never met in the same 'room'. Emoticons have been invented to minimize mis-communication and mis-interpreting folks thought meanderings. Plus they permit shorter sentences.
That's their "plus". Their "minus" is that emoticons are replacing good writing. The Victor Hugo, Balzac, Voltaire, Keats, ... of their times did not need emoticons to be understood but people back then read long books. That was the method of distraction.
