The term content furnace is often used when describing games that heavily rely on fresh content to sustain the interest of their players.
There's nothing wrong with creating highly focused, hand-crafted stories, but unless you're consciously aiming to deliver an experience with highly limited replay value, you'll have to plan for ways to keep the game seem fresh for longer. There are several ways in which you can limit content burn (or increase the amount of content to burn through) and hopefully keep your players' interest for longer.
