old != broken
> In practice, self-hosting email is problematic and presents risks
Not more, than self hosting WordPress.... And it's really not that problematic to self host it. I'm very tired of always hearing how hard it is when all one needs to do is adding a few dns records for spf, dkim, dmarc and reverse dns, and it works.
> At the same time, the utility and practicality of email is rapidly declining.
Not as infrastructure, no. In personal communication, yes.
You are correct on some points, especially the power concentration. On other points we're over complicating email. We need to accept that it'll never be as "private" as some enthusiasts would like it to be, but it's a more than adequate for reliably exchanging information.
I've hosted email for 40m+ users. It's nontrivial.
The underlying protocols are well over 40 years old (RFCs 822, 821, 733, 630, 561, possibly others), and are showing their age. (https://tools.ietf.org/html/rfc733)
In theory, email is universal and distributed, in practice it's very highly concentrated amongst a few major providers (Google's Gmail, Microsoft Outlook, Yahoo, as of 2016 http://blog.shuttlecloud.com/the-most-popular-email-provider...). Google alone has a majority of US email addresses. Some see this as a problem. (https://mako.cc/copyrighteous/google-has-most-of-my-email-be...)
In practice, self-hosting email is problematic and presents risks to the administrator, their correspondents, and third parties through possibilities of spam and other abuse.
At the same time, the utility and practicality of email is rapidly declining. I've used email for well over three decades, and defended the basic protocols until recent years. I can do so no longer, and actively avoid email in general for numerous reasons, something that does not please me in the least.
Unfortunately, getting protocols and standards un-stuck is exceedingly difficult, not just in tech and comms, but generally, and for deep and systemic reasons. Greenfield domains with a small but collaborative community seem best disposed to developing standards -- that's not what we have presently in the online / digital world.