> - No proof that people are who they say they are, we have PGP/GPG but no one uses it.

Do you have that proof with any other communication medium? You have some level of authentication provided by the service provider, sure (e.g. with the phone), but it's far from perfect and unspoofable.

- Related to the above, I can't control who can send me email, people use different email addresses and any address can be faked anyway.

> Same problem with phone calls, letters, faxes. Doesn't mean those systems are broken.

- No accepted way to post short messages, people still post long email with big disclaimers and/or adverts at the bottom

There are other protocols for this. I think it's fine that email doesn't solve everything.

> - Poor email client support for sending/receiving large numbers of pictures, with thumbnails and full versions

Sounds like a client problem.

> - Lack of any real semantic support tags, share a single link, geo information etc.

This is a problem with open protocols. Not everyone wants to share the same things you do.