Nothing new under the sun
This problem isn't new, I remember the paranoid freak-outs everyone had back when I was running a BBS back in the early 80's. the NSA/GCSB etc are watching us, recording our BBS sessions .... *sigh*
There is no such thing as 100%; 100% safe?, Nope; 100% secure? Nope.
Secure your data by putting it in a safe, wrap that in concrete & dump it in the middle of the ocean?
Someone could still get at your data, wouldn't be easy, but it could in theory be done.
So what is to be done? As many have already suggested, it's all a matter of cost vs ease of access, complexity
SSL/TLS covers many session based encryption problems not just https; pops, imaps & smtps all come as standard on most servers & clients even if they aren't always enabled/allowed by $yourVendor
If you don't want Yahoo or Google handing over your e-mails, set-up & run your own , Yeah I know that's beyond most home users, but surely not most el Reg commentards :)
The problem really comes down to this...
Every time $badThing happens people scream and yell that $someOne should have done something to stop $badThing
This is why the work at large is going from free -> police state
The other problem is the lie we tell ourselves and our children
"What to $otherPeople want?" ... well they are "just like you" they want what you want
This is why politicians are deathly afraid of everyone around them; they assume that everyone is a power hungry socio-path, "Just like them"
Mines the one with the keys to the Faraday shielded bunker in them