Supposedly Apple responded to someone that removing the 3D touch app switcher was not a bug. It's possible for it to get re-added, but seems like Apple is intentionally moving away from that. My guess is iPhone 8 will use a different app switcher (since it won't have a home button) and so Apple is removing the 3D touch method to avoid confusion. I'm also guessing that they have statistics on how many people actually use it, and it's probably close to nil...
So in order to compensate for the lack of a home button to double press on one device, they are instead going to require some sort of screen interaction to display the app switcher.
Wouldn’t then the 3D Touch feature that’s not present in the beta, but we’ve already had for years to get accustomed to, be such a solution? Might that not possibly be why it was introduced in the first place, baby steps in adding new features to acclimatise us to future changes.
I get what you’re saying, I’m sure Apple will have something great in store for the iPhone 8 and it’s new screen layout.
But the iPhone 8 is not the only iPhone, nor even the only new iPhone it would seem. So why punish the millions of people who have been using and enjoying 3D Touch for years.
Before switching to the beta I never used the home button to bring up the switcher, it was always pressing the left of the screen. It just seemed easier as my thumb would usually be closer to that than the home button.
Though I am entirely certain there will be as many, if not more, people who still stuck to the old way of using the home button. So I’m hoping Apple have a happy medium to suit all kinds.