If you think v6 isn't backwards compatible then literally anything bigger than 32 bits will never count as backwards compatible for you. The whole point of making the address space bigger is to make it bigger, so what do you expect to achieve by complaining that the result is incompatible?

As a human, I've found that e.g. "fd00::53" is perfectly readable to me, and most of the time you're interacting with strings like "news.ycombinator.com" anyway which is identical to how it works in v4, so I'm not sure how far I'd agree with that part either.