A world can spawn from a simple idea. Dont be so quick, Yahtzee might see a word on these forums and that word can start giving him ideas about his next game.
Oh crap, the reason Yahtzee is good is becouse he doesnt give a shit about what others think, about him or his work... if he starts "making everyone happy" then we'll be looking at a Deus Ex 2 or Resident Evil Outbreak 2.
Plus the consumer doesnt really know what they want, thats why thier the consumer.