I disagree that it's not useful—I have a really long password and suck at typing, so being able to mash the fingerprint sensor is really helpful.

But yes, it is very frustrating that every time there's a system update you have to redo it.

its not like you update everyday, once a month seems like a fair trade if it’s convenient.

Or just use Puppet to manage your macOS installation which makes things a lot easier ;)