Machine-id is read as plaintext by programs and transmitted as plaintext by programs.
[citation needed]
Anything that does that is spyware and if you're aware of anything that does this you should be doing us all a public service and sharing.
Hashing the unique id from the host side as opposed to trusting programs to read it and act in a way the user understands and deems appropriate is a much better method of handling calls to identify the equipment than just letting programs read your standardized unique id.
I can build something in maybe 10 minutes that will fingerprint your machine to like 99.99% uniqueness. This solution solves nothing. But now we're just repeating ourselves.
Go take it to the systemd folks yourself and see how they respond.