The decision to hold back on USB-C is 100% motivated by the licencing royalties the Lightning ecosystem generates and 0% motivated by environmental or consumer issues.

Apple happily uses USB-C in all its other products (including its TV remote) as well as adopting other universal tech industry standards like HDMI, DVD, Bluetooth and USB-A.

Lightning remains because of its bottom line contribution from the sheer volume of iPhone sales. Its pretty archaic by modern standards with its 2.0 transfer speeds.