I rarely see any exotics other than thorn or the last word in the crucible, red death sometimes makes an appearance but that's still not too often. Why do you think it is that so many people use these same guns? They outclass all other weapons and are incredibly easy to use, especially thorn. You don't even need to necessarily be good at the game to do good with thorn, most of the time you can just hide after getting a few shots in and let the poison do the work for you.