This is why I maintain that we need identity/security providers that will manage the keys and encryption schemes for you. The real problems are:
* Slashdot nerds (and the like) get all freaked out about the idea of a 3rd party managing people's keys. In order to be truly secure, it's necessary that only you can ever possibly get access to your keys, which means that you need to manage them yourselves. Therefore, any scheme that requires trusting a 3rd party gets rejected.
* Each vendor/developer wants to create their own standard, and then have everyone use their solution. No one works on real standards anymore. Facebook wants you to use Facebook Messenger. Apple wants you to use iMessage. Google wants you to use Hangouts. Or whatever. The point is, major companies are not working to come up with a cohesive modern secure messaging standard.
Now in answer to the first problem, I think to some degree, these people just need to get over it. Most people are sending unencrypted emails, so if they had their email encryption managed by Microsoft or Google, it would still be substantially more secure than it is now. The idea that some people might entrust their keys to a 3rd party should not be a bad thing, since most people are not qualified to manage their own encryption scheme.
What the nerds should want is only to be able to set up their own encryption key management if they feel it's necessary. Similar to the way many people use cloud email services, but you *can* set up your own email server, there should be simple cloud encryption/identity services, but people should still be allowed to set up their own encryption/identity servers.
The second problem is much more difficult. How do you get ubiquitous adoption of security standards where companies have an interest in maintaining incompatibility? I really don't know. One of the historically successful methods of creating an adoption of standards is through some kind of governmental action (either direct regulation, or requirements for government contracts). However, nobody trusts the government to push an encryption scheme, since they only want communication security when they can preserve a backdoor.
It's a shame. We really could do so much better if people weren't such idiots. And the problem isn't that "the common man" is an idiot, but that the people running various companies, and the people running the government, are all a bunch of idiots.