The thing is, doing it correctly still actually requires quite a bit of understanding.
The hard part has always been key management. If a user doesn't have a properly managed web of trust, they have no real assurance of privacy or authenticity.
I think the people who are actually in a position to fix this problem are the social networks. Imagine if the act of joining Facebook caused a keypair to be generated by you, and friending someone brought their key into your web of trust with some sensible defaults.
Unfortunately Facebook has no incentive to build such a thing. But maybe something third party can leverage all those social connections to help users manage keys in a more natural way.
I use enigmail + thunderbird, and it's pretty simple to use. It's only difficult because the tools are immature. Sending a mail and seeing a "verified from [email protected]", or "can only be viewed by [email protected]" isn't difficult to understand.
The smartphone vendors are in a unique position where they could make this happen.