A key aspect of IPv6 is that the address space is big enough that 'carving it up' for subnets is dramatically simpler even at the largest scales. You don't need to be frugal with network sizes, and you don't need central coordination to avoid conflicts. This is huge!
E.g.: If I want to deploy a cloud VPC (or vNET), then I have to go find "the guy with the spreadsheet" and peel off a tiny(!) private IPv4 address space. If he's away from his desk or on holidays, my 1-minute automation script will now take 1-10 working days until he's back and responding to requests. With IPv6 this just disappears as a bottleneck.
E.g.: If I want to deploy a cloud VPC (or vNET), then I have to go find "the guy with the spreadsheet" and peel off a tiny(!) private IPv4 address space. If he's away from his desk or on holidays, my 1-minute automation script will now take 1-10 working days until he's back and responding to requests. With IPv6 this just disappears as a bottleneck.