1. The difference in size(and it's really small in the first place) is really irrelevant. The ipad Pro is below 6mm in thickness, no phone on the market is close to that, actually phones has become thicker in recent years.
2. Lightning is the physical port actually and it supports USB 2.0 and 3.0 standards. USB C is also the physical port the only difference is that it can support much faster and better standards like thunderbolt 3, 4, 100w charging. This is not entirely relevant for phones. Also basically any USB C cable works with smarphones. I've yet to find a USB C cable that wasn't recognize by a smartphone.
3. According to the declared characteristics, the mechanical life of the USB Type-C connector is about 10,000 connections. I doubt lightning provides better mechanical life. The idea is that that "lip" isn't exposed, the same way the pins on the cable connection aren't exposed so breaking it is hard and happens only in extremely rare cases. Also because the pins for the lighting cable are exposed it provides opportunities for different damages. Like in the picture below:
4. That's not how USB C connections are, that's just your experience with an obviously not very great implementation of USB C on a monitor. I've owned many phones with USB C connectors and they all provide the same feedback when inserted as the lighting port on iPhones.
5. Apple has been providing multiple devices with USB C port for quite a few years, for some of their computers is thr only port. I haven't heard of any concerning reports of reliability or ability to repair.