> Email client have vastly different feature sets and capabilities. Most notably, the HTML support is very different from one browser to another.
That's hardly an email issue, that's a client issue. The mail protocol doesn't care much about the content.
Also, you will find some people averse to using HTML email.
> The vast majority of email systems do not even support encryption of the message itself
Again, that's not part of the email protocol itself, and as far as email encryption goes PGP is pretty much the standard. The real issue here is whether to use the sucky PGP/inline or the proper PGP/mime
> No random chat support
You mean randomly send an email to someone, without being invited ? That's pretty much what spam is.
> No group chat ( cc doesn't count as it lacks history of the group chat )
I don't see why cc wouldn't count, when combined with the various In-Reply-To: and Refenrences: headers, you can build a very solid group chat history.
> Have you ever received emails seemingly full of gibberish? Utf8 not supported properly in majority of implementations. ( which imo requires getting and using a font that supports the codepoints )
Again, a client problem, but I'll agree that clients can lie on the actual encoding that is used in emails. Mandating UTF-8 would be such a heaven.
> No user index ( saying that you could have an address book also doesn't count; and that is a seperate thing which also there is no one spec that is used by all people using email )
I don't understand. Why couldn't a server index your emails and extract your contacts ?
> No real time messaging support.
Theoretically, you can (and should) run an MTA on your machine; you'd then receive messages in real time
> server polling
Polling sucks, don't do it. If you don't have an MTA on your machine, at least use IMAP IDLE. Disclaimer: I wrote this (https://github.com/rakoo/idlewatch) to automatically sync all my mails when there's something new.