Any there a Force Touch feature?
Apple seldom locks features to only one product. Force Touch was first introduced on the Apple Watch but actually shipped first on the new MacBook. That shows it can be implemented on a wide range of products. So, again, why stop at just a few?
Also, the iPhone 3GS got speed, the iPhone 4s got Siri, the iPhone 5s got a fingerprint sensor, so why not give the iPhone 6s and iPhone 6s Plus some pressure sensitivity by way of Force Touch and the Taptic Engine? On the Apple Watch, Force Click is used to bring up context-sensitive menu options. On the Mac, to simulate a trackpad click—or multiple depths of click—and to allow for adaptable drawing.
A lot of that would be great on the iPhone.