Would you, in ~10 years, prefer a new standard (Signal-Mail, RFC 424242) and have "secure" (for a given definable threat model) standard called email that obsoletes the above RFCs and has 80% market share over current email standards...

...or have 30 different walled-garden, not-interoperable, partially-working (for a given ergonomic use case) apps?

Considering that much of present day communication happens on async on email (including important conversations inside and between banks, governments, land-lords and tenants....), I'd say its something that should happen. And if we can convince the right people, it will happen. We'll live for the next ~5 years in a state of hell (just like we do when we upgrade TLS protocols), and then for the majority of people, things will get better.

My 2c.