Think about it from this side... YOU are the gamedesigner. You watch over the hole project, you do not say in detail what the programmer or writer should do, you set the path for the actions those guys will do. When you are not good at writing than just inform yourself what they are doing, just staying in touch and stirring them into the right direction if it doesnt fit the idea of the game, thats what you do. Hope I wrote not to agressiv, i am sorry if my english isn't the state of the art. Hope I could help.