Earlier quoted context omitted.
I don't understand the hate. It's still a good way to send a password or some financial information, just because you know that it's going to be deleted soon and if in the future your contact's account is hacked it will be long gone. Basically, it's a secret chat for email.
Well, i wonder how they will make other mail providers (or clients, for that matter) to honour this kind of mail headers.
For users outside of Googles platform the obvious solution is either not to send them or to send a managed link to the message contents via normal email.
It can't be perfect thanks to the analogue hole, but it only has to be a bit better than nothing to provide utility.