Sometimes the key to selling a product is what the seller leaves out, but that was not much in the case of Apple's newest devices.

Apple went bigger than ever with the respective 4.7- and 5.5-inch screens of the iPhone 6 and 6 Plus. Then they unveiled their first ever smart watch, the Apple Watch, which is also the first iDevice completely void of Steve Jobs' fingerprints.

Even though Apple left its customers wanting for little, there are certain things Tim Cook and co. left out.

1.     Sapphire crystal screens

There was heavy speculation that Apple would be coating their new iPhones with the ultra-tough, scratch-resistant materials once the company teamed up with GT Advanced to produce the stuff. However, sapphire glass is only on the Apple Watch, as it is used to coat most watch faces.

Venture Beat cited unnamed sources who said the material failed multiple standard tests during the iPhone 6's production. Otherwise, the ultra-tough material would be serving as the handset's screen. Other rumors suggested the amount of sapphire glass needed was too costly for Apple to produce without raising the iPhone 6's price. Some other outlets speculated Apple could not produce enough of it in time for shipment.

2.     The Apple Watch's battery life

Apple was pretty vague on this in their unveiling event, quite possibly because they knew their customers would just be excited enough to see the device. According to BGR, the smart watch's battery life is already something Apple wants to improve. The New York Times suggested the Apple Watch's design is so robust that it will actually be detrimental to the battery life.

Apple was already late to the smart watch market, so they need to hope the device does not flop with its customers over something as basic as battery life.

3.     HealthKit

Shortly before the official release of iOS 8, the Associated Press reported, Conn. Attorney General George Jepsen is expressing concern over the HealthKit app's security. The app is supposed to record and store health-related data. That is apparently too broad for Jepsen's liking and he is working to discuss his concerns with Apple's leadership.

One of Jepsen's main concerns involves the Apple Watch and how the device will collect the information it needs to cooperate with the HealthKit app. Jepsen has also raised this issue with Apple competitors, like Google upon the release of the Glass device.

4.     HomeKit

Apple may not be ready to show the world its progress on the application that will connect a user's home to their Apple devices. Customers know it is coming, but did not get to see Tim Cook turn the auditorium lights off from his wrist or arm his home security system via his iPhone.