There's a certain kind of player who thinks to himself "Hey, how can I annoy people and make the game less fun for everyone without getting punished?". That's the kind of player who spams taunt all game.
Uh, that's not what I think at all. Mostly I think "this taric emote is so ****ing outrageous must use more". The other day I used Tryndamere's "you never stood a chance" a lot in an aram. Then we lost, and I used it just as the game was ending. I do it mostly because it's funny (using it as you die), and just a wee bit to tickle people (it legitimately baits people into attacking you as well, spamming at the preminion showdown in aram makes people do stupid things and die for them).