IPv4 addresses are still manually assigned, so it still makes sense… smaller routing tables… faster to search for exit interface for each packet…

But mark my crazy words, one day, a computer cluster will automatically handout IPv6 addresses blocks, to administrators request and approval, based on minimizing routing tables. And when that day happens, they will invent a giant defrag process for IPv6 as well, to move contiguous blocks, and automatically update the IPv6 DNS process as well.