It's no huge loss if the sea takes all the cat photos off my phone. But if you're a hospital or civil services admin hooking up your operation to the Internet, you gotta be prepared for it all to go out to sea one day, because it will. Is that worth the gains?
(Possibly even negative, when people go out and deliberately install apps that, by backdoor or by design, hoover up their data, etc. And when the mainstream OSes are disincentivized to prevent this because it's their business model too.)
There was a time, not very long ago, when I could just tcpdump my cable-modem interface and know what every single packet was. The occasional scan or probe stuck out like a sore thumb. Today I'd be drinking from such a firehose of scans I don't even have words for it. It's not even beachfront property, we live in a damn submarine.
Well, no home is burglar-proof either. Just like with computer security, we define , often just implicitly, a threat model and then we decide which kind of security measures we use to protect our homes. But a determined burglar could still find a way in. And here we get to a classic security consideration: if the effort required to break your security is greater than the benefit obtained from doing so, you're adequately protected from most threats.