Well they asked everyone to agree on a standard 10 years ago, but that didn't happen (just because of Apple). So now they forcefully decided.
Why? No idea. It's a much slower standard, and puts the wearing parts in the port instead of the cable. USB-C is designed by committee, sure, but the port itself is better than lightning in nearly every consumer metric there is.
Beyond that, the springloaded contacts are on the cable end with type-c, with lightning it's inside the phone. I don't think it's a particularly common failure mode, but having less moving parts in the expensive bit is generally a good idea.
USB-C exists because Apple was in the process of creating Lightning. Also, in my experience, you seem to have the fragility point backward: the nub on lightning cables may break, but the port is fine, while the reverse is true for USB-C, where the fragile bit is in the port.