i've seen a number of people just turn into mindless trophy hunters (achivement hunters) and while a few might add replay value, it's rather stupid to have some games give trophies for sitting through the opening cinematic or making a new game. Trophies are filler in it's basest form. Trophies add nothing to the story or really change the game in any way, it just trains gamers like one would train a dog.
you work so hard to hear a trophy pop and you practically drool hearing the noise
dogs are taught to do tricks on the basis that if they do they're given a treat and the owner rings a bell doing so makes them drool for it.
Game designers may choose tough trophies to keep you from turning your disk in at a local gamestop in a secondary measure to avoid used game sales, even juno who's not really a trophy nut is very apprehensive at getting rid of a game on the basis he may go back for the trophies.