It’s not hard to remember IPv6 addresses for DNS servers assuming your addressing plan reserved the right subnets for anycasted services.
Remembering IP addresses stops being a thing pretty quickly. If anything the challenge shifts to remembering airport codes.
If you are typing them by hand that often even in IPv4 networks I'd be worried about typos and insufficient automation.
I think it’s more that small and medium organizations just don’t have any incentive to change (and plenty of incentive to not take the risk of change) leading to the numbers we see at https://ipv6-in-real.life/