One important difference is with IPv4, you have CIDR, so you can utilize a much, much greater percentage of the 2^32 addresses than you can of the 2^128 IPv6 ad

One important difference is with IPv4, you have CIDR, so you can utilize a much, much greater percentage of the 2^32 addresses than you can of the 2^128 IPv6 addresses, which, for the most part, has subnetworks that are /64 (you will never see a /70 IPv6 network). I think what's much more interesting about IPv6 is the number of networks with "effectively" unlimited number of hosts that you can have on them. We routinely have IPv6 networks that have 15-20,000 hosts on a single mesh subnet, and there is zero effort required to support that. Trying to design a network that might have as few as handful or as many as 32,000 hosts on IPv4 subnet would be a nightmare I don't even want to consider - even taking into account the impossibility of network assignment, there is the lack of SLAAC - you end up having to rely on things like DHCP, which, while wonderful for small networks, turns out to be a pain in the butt when you have a combination of mobility and millions of nodes.