I read a few months ago that an Apple exec acknowledged that transitioning suddenly to an all 4 USB-C port was too fast. I think what Apple could have done was offer the 2016 Macbook Pro with two USB-C ports and two old style USB 3 ports to make the transition less jarring. Like what they did with 2017 iMac Pro. Transitioning from 1 port technology to a different one with an overlap has been done by Apple before. From Firewire 400 to Firewire 800 had both ports present on specific year Macs and from Firewire 800 to Thunderbolt 1 also had both ports present on specific year Macs. I could not find a Firewire 800 port & USB 3 port present on 1 single Mac model though. A all Thunderbolt 3 would have made more sense in say 2019 or 2022?