No. UTF-8 is for encoding text, so we don't need to care about it being variable length because text was already variable length.

The network addresses aren't variable length, so if you decide "Oh IPv6 is variable length" then you're just making it worse with no meaningful benefit.

The IPv4 address is 32 bits, the IPv6 address is 128 bits. You could go 64 but it's much less clear how to efficiently partition this and not regret whatever choices you do make in the foreseeable future. The extra space meant IPv6 didn't ever have those regrets.

It suits a certain kind of person to always pay $10M to avoid the one-time $50M upgrade cost. They can do this over a dozen jobs in twenty years, spending $200M to avoid $50M cost and be proud of saving money.

Fixed that, thank you!

Regex? Did you link to the wrong page? I see no regexes on that page.

That's a problem with programming languages having inconsistent definitions of length. They could be like Swift where the programmer has control over what counts as length one. Or they could decide that the problem shouldn't be solved by the language but by libraries like ICU.