Being able to access legacy systems from new ones is a good property of new systems. This workaround is important.

(Also that may be done on routers which today deal with NAT anyway)

This isn't a workaround; it is a kludge. There are far better solutions in this problem space (some mentioned in this very thread).

Yeah I don't get it. If you need to access IPv4 for legacy reasons then dual stack seems like the solution here. Yes it's a lot of overhead since you have to deal with an IPv4 and IPv6 routing table. AFAIK Windows has had both enabled by default for a long time.

An average user is not expected to do that. But I understand there are mobile operators out there who have been doing this (instead of NAT) for a while because they don't have IPv4 addresses for ever consumer subscription? Wasn't T-Mobile US one of them? (Not living in the US.)

An average user shouldn't be able to find hardware not supporting IPv6, because it shouldn't be allowed to be sold. (And soon, hardware supporting IPv4.) Just like it happened with digital TV standards.

Yes. Like EU making mandatory the standard for phone chargers.

This is actually a very good workaround/transition mechanism, because it lets you go fully IPv6 native, keeping the translation layer for things that absolutely must use IPv4.

And after transition is done, in theory, all you’d do would be turn off the translation box. In practice you’ll have to keep it up until the end of days, but that’s a separate matter.

Thank you very much for approving my idea!

In home network single $70 USD device with 2 daemons running may be clearly too much but for corporate or even office network it's just one more box in addition to dozens of network devices.