That makes a lot of sense. Smileys aren't very natural for text within paragraphs because paragraphs can convey tone as a whole entity. But for those of us who learned to type in chat/IM environments, smileys make a huge difference because you don't have a whole entity to reference in that situation. A conversation is a stream of statements, so if someone says "you stupid jerk!" in IM, you're expected to reply -- but in a conversation it would be clear that they really mean "you stupid jerk! =P" through tone and facial expression. So that's how people naturally become smiley-dependent.