Amazon must have concluded that people with Kindle hardware would be more likely to buy books than those with who have Prime but an iPad which uses the Kindle, Nook, and iBook stores to name a few.
Maybe they'll loosen that restriction after the holidays when the free Prime trials from the initial round of Kindle Fire sales will have expired, potentially adding many new Prime subscribers.
Maybe they'll loosen that restriction after the holidays when the free Prime trials from the initial round of Kindle Fire sales will have expired, potentially adding many new Prime subscribers.