I believe that most users will not change the default settings, but a handful of people who need to connect to peripherals at any time can be manually disabled:
Connected via USB when 'USB accessibility' is enablediPhoneAt that time (such as syncing with iTunes on a computer), iOS will require the user to enter Passcode.
However, even if data communication is not possible, the device can still receive power through the USB port.
This setting is an extension of the "USB Restricted Mode", which has been tested on iOS 11.4 beta:
The USB throttling mode was designed to disable USB access 7 days after the lock, but iOS 12 drastically reduced this interval.
In other words, unless you connect immediately after you get your iPhone, there is no way to use a crack device such as GrayKey.
For this matter, I believe that the most dissatisfied is the law enforcement agencies for crime forensics. But from the customer's point of view, this setting helps to keep away from hackers and other ulterior motives.