Speaking as an app developer, the little-known nature of 3D Touch means we can never rely on it as the sole way to access a feature, and that pretty much always means we have ignored building much with it.
I wonder if better training by Apple could help? But it seems they’ve already accepted the tap-and-hold workaround for supporting some 3D Touch functionality on devices without 3D Touch.
Seems like 3D Touch, and iOS 7’s lightboxing parallax effect for backgrounds, was likely part of a broader vision by Ive and the design team to bring depth to a thin phone screen. It’s an admirable goal, but whether by lack of discoverability or lack of training, seems like it isn’t poised to be a widely-adopted technology.
There's a broader issue with the loss of discoverability. It's not exclusive to iOS, but the loss of the home button on the iPhone X and the replacement with gestures seems to mark a significant backwards step. Perhaps this is tolerable or even necessary given the increasing complexity of mobile user stories and maximal screen-to-body ratios, but it poses a lot of challenges.
Mobile is increasingly looking like desktop in terms of the gulf between "ordinary users" and "power users"; applications designed of one group are likely to be highly sub-optimal for the other, presenting developers with a difficult UX compromise. Most users understand the hamburger menu, which could be read as a sign of progress or a dismal failure.
I think the problem is that it's not available everywhere on all mobile devices (Android, iPads and older iPhones don't have it) so it's not utilized well or implemented as much as it could be, nor is it a universal behavior users can internalize like they do with panning and pinch to zoom. Android somewhat mimics it with long pressing, but iOS also has long pressing as well as 3D touch. Without ubiquity it can't become a primary UI mechanism, only tacked on to something that must work without it.
Personally though I don't think 3D touch is any less discoverable than your right mouse button on a computer. If you have a 3D touch capable device you had to configure it at least once when you got a new device capable of it so you know it exists just like you know a right mouse button click state often exists (Macs don't even ship with obvious right-click capability, the OS has it disabled by default and neither of their mouse input types have an obvious right click mechanism just by looking at them)
I wonder if better training by Apple could help? But it seems they’ve already accepted the tap-and-hold workaround for supporting some 3D Touch functionality on devices without 3D Touch.
Seems like 3D Touch, and iOS 7’s lightboxing parallax effect for backgrounds, was likely part of a broader vision by Ive and the design team to bring depth to a thin phone screen. It’s an admirable goal, but whether by lack of discoverability or lack of training, seems like it isn’t poised to be a widely-adopted technology.