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 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.

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 every consumer subscription? Wasn't T-Mobile US one of them? (Not living in the US.)

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.