If true, I would guess that this is not Tim Cook's decision, but Jony Ives, based only on visual design ideals. Even though I wish the current iPhones had a headphone port, I can see why the port was omitted from the iPhone: size and water-resistance. But the iPad? That's just silly. There's lots of room for a 3.5mm headphone port on the iPad, even the iPad Mini. Same with the 12-inch MacBook. I get why it only has a USB-C port. But the MacBook Pros? What's with the whole "USB-C only" thing? That's why I still have a 2015 MacBook Pro, for the extra ports and the SD card slot. As many people observed in 2016, when the current body style MacBook Pro was released, the product had actually lost functionality compared to the previous model. Sure, visual design is important, but not at the expensive of function. We are now a full two years on from that mid-2016 release, and MacBook Pro owners still have make sure they keep their adaptor dongles handy.
Apple should remember that the reason people have liked their products so far is: "It just works".
I have held off getting one of the new MacBook Pros because I could imagine the disaster of turning up at an important meeting with my MacBook Pro, but without a dongle, and having to say: "Sorry folks. It doesn't work."