You can use static assignment for the /64 host portion. Having a large prefix to work with for the subnetting actually makes managing a large number of devices

You can use static assignment for the /64 host portion. Having a large prefix to work with for the subnetting actually makes managing a large number of devices easier because you can group them into logical subnets, and in a way that future-proofs expansion. Coffeen covers this in IPv6 Address Planning. And on top of that you get way more efficient routing.