Astute observation by Brooks:
If you are arguing in favor of consolidating the gestures, then the better argument is just to get rid of 3D Touch. There’s no reason to have both 3D Touch and long press if they both do the same thing and since not all new [devices] have 3D Touch — 3D Touch would be the technology to be removed.
The whole point of 3D Touch is that it adds new functionality to iOS. It isn’t simply a different interpretation of an existing gesture.
When the iPhone launched with a multitouch display, there was really only one aspect of the system that required multiple touch points: pinching to zoom web pages and photos. Many years later, we now have the ability to adjust a map’s perspective, manipulate the depth-of-field in an Instagram photo, and play instruments on an iPad. All of these features — and many more — are made possible because the hardware can accept multiple touch points. 3D Touch is, I think, set to do the same thing given some time.
In some ways, I wish Apple shipped a lesser amount of 3D Touch functionality and simply waited to see how developers would interpret it. What they have shipped ultimately feels right, more or less, though.