If it doesn't make sense to put a world in a particular EP, then it's better to use those resources for good game-enhancing gameplay. I always love a new world, but packs should not be half-baked bc of adding an unnecessary world.
Edit: that being said, I'd also be willing to buy GPs that are built almost entirely around a world (thus a world pack). Worlds are important bc they make the game more replayable - one story told in 10 different environments (and slightly altered according to the theme of each world) will be different each time. BUT gameplay is more important bc if the sims and their stories are shallow, they are just sitting in pretty boxes and we (the players) get very bored.
