We are talking about addresses, not counters. An inherently hierarchical one at that. If you don’t use the bits you are actually wasting them.
Bullshit.
I have a 64-bit computer, it can address up to 18.4 exabytes, but my computer only has 32GB, so I will never use the vast majority that address space. Am I “wasting” it?
All the 128 bits are used in IPv6. ;)
Yes they are all “used” but you don’t need them. We are not using 2^128 ip addresses in the world. In your own terminology: you are using 4 registers for a 2 register problem. That is much more wasteful in terms of hardware than using 40 bits to represent an ip address and wasting 24 bits.
How is that not enough? It’s in standard ISO8601 format and can unambiguously be reduced to a UTC timestamp, which is all that matters.