I do understand the reasons behind it, and agree to them in principle.

In my case it's that I have a couple of "static" machines (work and home plus some laptops) and occasionally
boot live systems from USB-stick on other machines, and then there's also the occasional "cookie-amnesia"
even on my static machines.

Getting that email isn't the big problem after all, but having to get the link from phone to the target machine
is awkward.

Maybe, there could be a second link in the Mail labeled "Allow other machine access" and I'd click
that link whenever it's not the same as the one I'm reading mails on. After that, I'd click some link
on the target machine's "Wait for confirmation"-postlogin-page and then be really logged in.
I think it would still be safe, as only the machine that "just tried"(and thereby triggered the mail)
would be granted access.