Apple's new iPhone 11 and iPhone 11 Pro quietly ditched a feature that was first introduced 4 years ago

As soon as users got their hands on the iPhone 6S, complaints with 3D Touch started to surface.

Some users pointed out that 3D Touch mostly served to add more menu items that didn't exist before, arguably needlessly complicating the phones' interface.

"Its use often amounted to the right click of a mouse, which is funny coming from the company that famously refused to put a dedicated right button on its mice or trackpads," Jacob Kastrenakes wrote in The Verge.

Others voiced confusion about when 3D Touch could be used.

"It's baffling that there's no visual indication of what can be 3D touched," Apple pundit John Gruber pointed out.

A recurring criticism of 3D Touch was that it didn't seem necessary for navigating an iPhone, and accordingly, some users simply didn't use it.

In an early hands-on review of the iPhone 6S from CNET, one user was impressed by the technology behind 3D Touch, but remarked that "I'm not sure I'd really use this."

Others, like StackOverflow cofounder Jeff Atwood, disabled the feature and said they didn't miss it. "Kinda forgot it existed," Atwood wrote on Twitter.

A year before Apple debuted 3D Touch with the release of the iPhone 6S, it unveiled a similar technology on the first Apple Watch, dubbed Force Touch. Force Touch was later added as a feature on MacBook Pro trackpads beginning in 2018.

The technology is essentially the same as 3D Touch, but can only detect two levels of input based on sensitivity, while 3D Touch can detect three.

"3D Touch" is also a less awkward turn of phrase than "Force Touch," a title that critics pointed out sounds oddly violent out of context.

In terms of interface, Haptic Touch doesn't present new forms of input in the way that 3D Touch did. The iPhone 11 and iPhone 11 Pro will differentiate between a press and a long press, like all former iPhone models.

The difference is that the new iPhones will provide haptic feedback, or small vibration jolts in response to long presses to make the interface more intuitive.

This feature already exists on the iPhone XR, and on the home button of the iPhone 7 and later models.

Despite its flaws and widespread shaky reputation, some have spoken up in defense of 3D Touch now that it seems Apple is scrapping it.

Proponents have pointed out that in some instances — like playing live photos — 3D Touch provides more options than a long press is capable of. And for users who adjusted to it, 3D Touch can feel more natural.

"The vibrational feedback is stronger and more satisfying to the press, and 3D Touch is also noticeably faster than Haptic Touch," Mashable critic Raymond Wong argues.

It's unclear if 3D Touch will ever return, but its disappearance from all three newly-announced iPhone models suggests that it may be gone for good.