Water damage kills large numbers of phones every year and the industry has been very slow to do anything about it.
Except for Sony.
The Xperia line has traditionally integrated weather resistance into its premium and some mid-range devices. Other manufacturers have either restricted such protection to a single device or ignored the concept completely.
The argument has always been that sealing flaps against water ingress is an annoyance users aren't prepared to accept. Sony has gradually worked to remove this frustration. First by creating a headphone socket that was self-sealing (for the Xperia Z1) and now, with the Xperia Z3+ doing the same for the charge/sync port.
So if Sony can make a device which is IP68 compliant without any flaps there is no reason for other manufacturers to not do the same.
As customers we should demand nothing less.