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.

I didn't want to encourage non-standard behavior, but you are correct. Tunnels are a common use the same way /31s can be used in IPv4.

Going smaller than /64 is against best practice and unnecessary. People coming from IPv4 need to understand that trying to be careful with subnet sizing for purposes of preserving space is not a thing in IPv6 below /64. Maybe if a residential user has a /64 from their crappy ISP settings they'd need to do it, but not in a properly configured scenario and certainly not in enterprise.