What am I missing?
Right now, nothing major. At some point the big companies (Google, cloud flare, etc) may very well tire of having to pay more and more for ipv4 address that they may provide incentives for IPv6 (eg they could start throttling IPv4). There are some early moves going on already here. AWS used to only charge for unused IPv4 elastic IP addresses and now charge for them regardless of their use.
Honestly, the next time you upgrade your gateway/router you may as well set it up to be ready, but you're otherwise not missing anything right now. You can also use IPv4/v6 at the same time. You can enable it on your router and your IPv4-only devices will still work perfectly fine. One note, auto-discovery on IPv6 was a bit of a shitshow (SLAAC, IPv6 auto-addressing, and DHCPv6 all were a thing and the original auto-addressing didn't even support getting DNS servers), but things are settling on SLAAC (though ISPs will be using dhcpv6 for a loooong time).