> If you're going to go through all of that trouble why only do a half measure.
Because a "half measure" would have been easier to adopt, therefore would have been more likely. The strategic error IPv6 made was, I think, taking the point of view that as long as a breaking change is necessary, then increasing the scope of that change doesn't bring greater cost.
But it does, quite a lot of it, and that greater cost is the primary reason why IPv6 adoption has suffered.
Because a "half measure" would have been easier to adopt, therefore would have been more likely. The strategic error IPv6 made was, I think, taking the point of view that as long as a breaking change is necessary, then increasing the scope of that change doesn't bring greater cost.
But it does, quite a lot of it, and that greater cost is the primary reason why IPv6 adoption has suffered.