Personal data could be obtained already. It has been definitively proven that data is bought and sold... fobbed off as leaks and hackers...
Again I don't understand your point. Yes data is stolen, sold etc, but risks can be reduced and that is the point of the OP. You can get through any front door but that doesn't stop many people locking it and taking extra precautions - each reducing risk of someone breaking in. Some may not bother locking their door but that doesn't mean others would choose not to.
With gmail my mum uses it for some basic stuff, I can't see much risk of her usage becoming public. I use my email for much more and would not.