I had a waterproof phone last year
I had one once. For about a month, until it fell in the water. So much for that idea. It kind of annoys me that I can wash a camera and lens under the tap to get salt water off it, but I can't even expose my phone to water for 10 seconds. You'd think a complex assemblage of sliding plastic bits would be *less* waterproof, not more.
USB-C appears to have to have fairly weak retention
I think this is a feature, and I suspect they're expecting that anything modern enough to have the connector will be running modern software that copes with disconnection. They're wrong, obviously (says the guy who has a Windows XP virtual machine because that's the most recent OS that will talk to some of my USB devices... and they will connect viz a USB-C connector soon). Amusingly the Windows Me VM talks quite happily over "a serial port" provided by a USB-to-serial device that the WinMe OS can't detect, let alone load drivers for.