I've not familiar with Dungeon World, and I have not played 13A, but IME 4e, though great, definitely need some fine tuning. I agree with @Lanefan that every system does. I don't think I would want to play one that didn't! Fixing / tweaking things to my taste is half the fun!All I can say is, my three favorite systems--4e, 13A, and Dungeon World--didn't need this. It's part of why they're my favorite systems.