For starters, Apple often sells their OWN case products for their devices, so they have no vested interest in making sure 3rd. party case designers get an early jump on case production. (EG. the rubber bumper cases for the iPhone 4)
Apple's stance seems pretty simple: Let us RELEASE the product first, and THEN you guys get your hands on one of the final products and design your accessories around it.
Case makers who are so desperate to launch products faster do so completely at their own risk (and yes, they're going to take chances - knowing the risks involved, because they stand to make serious $'s if they've got one of the only available cases for a new phone on launch day).
IMO, it's still not out of the realm of possibility that the rumored iPhone 5 they designed those early cases for will turn out to be accurate as the phone released *next* year. Maybe they were simply seeing very early prototypes of the next gen. phone and they've simply produced a product way too early?