This is Apple's fault for requiring special hardware when other phone manufacturers have no problem providing equal functionality over what is essentially standard hardware. This is yet another "we refuse to follow industry standards and force our customers to buy 20 adapters (read: everything) directly from us or a PPPP (potentially-patent-paying-partner)" game. Given their history, find it interesting that they're putting USB-C on some of their laptops. But if not already, they'll probably eventually require that some proprietary chip be installed before their equipment will accept a charge from an otherwise standard device.
Personally not interested in plugging my phone up every time I pop in the car.
Intel, Microsoft and Linux-based devices including Amazon & Google already have some level of support for MiraCast wireless display standards. (Apple though Linux/BSD-based, refuses because they want everyone to pay big bucks for their proprietary AirPlay solutions.) If BlueTooth had the bandwidth everyone would probably use that standard but it doesn't. So I think they use the WiFi adapter to multi-point connect.
Hopefully they're working on Wireless Display and are using wired as a quick stepping stone.