New and different content types is only half the problem.

Everything in this game except housing is easily replaceable garbage including gil; nothing has any value. People may not like rare nm drops and the competition it brought, but those drops had value; they made gil have value in ffxi. I don't know about others, but that alone was enough to keep me hooked on xi, because not only did it have different content types, but they all had rare drops or at least something of worth in that game.