> Absolutely madness and probably makes at least 80% of the phone’s functionality completely undiscoverable and inaccessible unless you already know it is there.
Well, that can't be strictly true, since no one is born knowing these things, yet people do learn about them. I don't think it's crazy to expect people to desire to read a quick guide or watch a quick video about UI paradigms/tricks/shortcuts for what is likely to be one of the most complex and most frequently used electronic devices in their lives.
I do agree that 3d touch is a bad idea, because there's no pattern to learn other than very specific per-application places it can be used. If there was some visible UI hint that an element was 3d touchable, perhaps I would be more of a fan.
As for the double-click and triple-click stuff, I can't really think of that many examples on iPhone. I believe triple-clicking a physical button can be used to enable accessibility features? I think it's pretty acceptable to have accessibility features that drastically transform the phone's user experience fairly hidden, as long as they're well documented for the people who need them.