These message icons are not a novelty anymore (after the first half-an-hour that you see them). They are just annoying to the eye, and you have to look twice to sort through the list of new/old messages.
A funny icon might draw attention to a special message, but if EVERY message has one, then you just ignore them, so there is no use for them!
A funny icon might draw attention to a special message, but if EVERY message has one, then you just ignore them, so there is no use for them!