Honestly, if IPV6 had been v4 but with 2 extra octlets, I believe we would be at close to 100% adoption. And also wouldn't run out of ips anytime soon.
They haven't done many of the changes for fun but because it makes some things work better i.e. using multicast instead of a broadcast in many places compared to IPv4. Enabling and making autoconfiguration a lot more integral. Making the smallest standard prefix /64 (with P2P being /127) - eliminating basically all thinking about how many hosts can I fit in a subnet.
There are things with MTU and fragmenting that are partially more complicated but in a sense also simpler than IPv4.
