The length isn’t the only thing that makes the ergonomics suck. The lack of backwards compatibility sucks. The “you don’t have to use NAT anymore” is great theoretically, but it renders a lot of casual network maintainers mental model of network security obsolete without a clear and simple alternative. The shorthand is not intuitive (though it’s not CIDR-level counterintuitive). Really, there’s way too much about working in IPv6 that’s not intuitive with even very solid IPv4 network knowledge.

So yeah, having to relearn a bunch of basic network knowledge that worked just fine for decades is a PITA, and I’m 100% positive a design process that focused more on the people that need to configure networks could have yielded a much friendlier, and therefore a much easier to adopt standard.